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Message-ID: <bdbfedd5-11bb-42f2-8548-b7157903b936@foss.st.com>
Date: Mon, 13 May 2024 11:21:18 +0200
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Subject: Re: [PATCH 05/12] dmaengine: Add STM32 DMA3 support
To: Frank Li <Frank.li@nxp.com>
CC: Vinod Koul <vkoul@kernel.org>, Rob Herring <robh+dt@kernel.org>,
        Krzysztof
 Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley
	<conor+dt@kernel.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre
 Torgue <alexandre.torgue@foss.st.com>,
        <dmaengine@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>, <linux-kernel@vger.kernel.org>,
        <linux-hardening@vger.kernel.org>
References: <20240423123302.1550592-1-amelie.delaunay@foss.st.com>
 <20240423123302.1550592-6-amelie.delaunay@foss.st.com>
 <ZjYst0rpC4zM5fs1@matsya> <01952335-7364-46ac-b02d-268c2ebd7e66@foss.st.com>
 <ZjqOgBWrYEM5/8BL@lizhi-Precision-Tower-5810>
Content-Language: en-US
From: Amelie Delaunay <amelie.delaunay@foss.st.com>
In-Reply-To: <ZjqOgBWrYEM5/8BL@lizhi-Precision-Tower-5810>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 7bit

Hi Frank,

On 5/7/24 22:26, Frank Li wrote:
> On Tue, May 07, 2024 at 01:33:31PM +0200, Amelie Delaunay wrote:
>> Hi Vinod,
>>
>> Thanks for the review.
>>
>> On 5/4/24 14:40, Vinod Koul wrote:
>>> On 23-04-24, 14:32, Amelie Delaunay wrote:
>>>> STM32 DMA3 driver supports the 3 hardware configurations of the STM32 DMA3
>>>> controller:
>>>> - LPDMA (Low Power): 4 channels, no FIFO
>>>> - GPDMA (General Purpose): 16 channels, FIFO from 8 to 32 bytes
>>>> - HPDMA (High Performance): 16 channels, FIFO from 8 to 256 bytes
>>>> Hardware configuration of the channels is retrieved from the hardware
>>>> configuration registers.
>>>> The client can specify its channel requirements through device tree.
>>>> STM32 DMA3 channels can be individually reserved either because they are
>>>> secure, or dedicated to another CPU.
>>>> Indeed, channels availability depends on Resource Isolation Framework
>>>> (RIF) configuration. RIF grants access to buses with Compartiment ID
>>>
>>> Compartiment? typo...?
>>>
>>
>> Sorry, indeed, Compartment instead.
>>
>>>> (CIF) filtering, secure and privilege level. It also assigns DMA channels
>>>> to one or several processors.
>>>> DMA channels used by Linux should be CID-filtered and statically assigned
>>>> to CID1 or shared with other CPUs but using semaphore. In case CID
>>>> filtering is not configured, dma-channel-mask property can be used to
>>>> specify available DMA channels to the kernel, otherwise such channels
>>>> will be marked as reserved and can't be used by Linux.
>>>>
>>>> Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
>>>> ---
>>>>    drivers/dma/stm32/Kconfig      |   10 +
>>>>    drivers/dma/stm32/Makefile     |    1 +
>>>>    drivers/dma/stm32/stm32-dma3.c | 1431 ++++++++++++++++++++++++++++++++
>>>>    3 files changed, 1442 insertions(+)
>>>>    create mode 100644 drivers/dma/stm32/stm32-dma3.c
>>>>
>>>> diff --git a/drivers/dma/stm32/Kconfig b/drivers/dma/stm32/Kconfig
>>>> index b72ae1a4502f..4d8d8063133b 100644
>>>> --- a/drivers/dma/stm32/Kconfig
>>>> +++ b/drivers/dma/stm32/Kconfig
>>>> @@ -34,4 +34,14 @@ config STM32_MDMA
>>>>    	  If you have a board based on STM32 SoC with such DMA controller
>>>>    	  and want to use MDMA say Y here.
>>>> +config STM32_DMA3
>>>> +	tristate "STMicroelectronics STM32 DMA3 support"
>>>> +	select DMA_ENGINE
>>>> +	select DMA_VIRTUAL_CHANNELS
>>>> +	help
>>>> +	  Enable support for the on-chip DMA3 controller on STMicroelectronics
>>>> +	  STM32 platforms.
>>>> +	  If you have a board based on STM32 SoC with such DMA3 controller
>>>> +	  and want to use DMA3, say Y here.
>>>> +
>>>>    endif
>>>> diff --git a/drivers/dma/stm32/Makefile b/drivers/dma/stm32/Makefile
>>>> index 663a3896a881..5082db4b4c1c 100644
>>>> --- a/drivers/dma/stm32/Makefile
>>>> +++ b/drivers/dma/stm32/Makefile
>>>> @@ -2,3 +2,4 @@
>>>>    obj-$(CONFIG_STM32_DMA) += stm32-dma.o
>>>>    obj-$(CONFIG_STM32_DMAMUX) += stm32-dmamux.o
>>>>    obj-$(CONFIG_STM32_MDMA) += stm32-mdma.o
>>>> +obj-$(CONFIG_STM32_DMA3) += stm32-dma3.o
>>>
>>> are there any similarities in mdma/dma and dma3..?
>>> can anything be reused...?
>>>
>>
>> DMA/MDMA were originally intended for STM32 MCUs and have been used in
>> STM32MP1 MPUs.
>> New MPUs (STM32MP2, ...) and STM32 MCUs (STM32H5, STM32N6, ...) use DMA3.
>> Unlike DMA/MDMA, DMA3 can be declined in multiple configurations, LPDMA,
>> GPDMA, HPDMA, and among these global configurations, there are possible
>> sub-configurations (e.g. channel fifo size). stm32-dma3 uses the hardware
>> configuration registers to discover the controller/channels capabilities.
>> Reuse stm32-dma or stm32-mdma would lead to complicating the driver and
>> making future stm32-dma3 evolutions for next STM32 MPUs intricate and very
>> difficult.
> 
> I think your reason still not enough to create new driver instead try to
> reuse old one.
> 
> Does register layout or dma descriptor is totally difference?
> 
> If dma descriptor format is the same, at least you can reuse prepare DMA
> descriptor part.
> 
> Choose channel is independt part of DMA channel. You can create sperate
> one for difference DMA engine.
> 
> Frank
> 

stm32-dma is not considered for reuse : register layout is completely 
different and this DMA controller doesn't rely on descriptors mechanism.

stm32-mdma is based on descriptors mechanism but even there, there are 
significant differences in register layout and descriptors structure.
As you can see:
/* Descriptor from stm32-mdma */
struct stm32_mdma_hwdesc {
	u32 ctcr;
	u32 cbndtr;
	u32 csar;
	u32 cdar;
	u32 cbrur;
	u32 clar;
	u32 ctbr;
	u32 dummy;
	u32 cmar;
	u32 cmdr;
} __aligned(64);

/* Descriptor from stm32-dma3 */
struct stm32_dma3_hwdesc {
	u32 ctr1;
	u32 ctr2;
	u32 cbr1;
	u32 csar;
	u32 cdar;
	u32 cllr;
} __aligned(32);

Moreover, stm32-dma3 can have static or dynamic linked-list items. 
Dynamic data structure support is not yet in this patchset, current 
implementation is undergoing validation and maturation.
"cllr"  configures the data structure of the next linked-list item in 
addition to its address pointer. The descriptor can be "compacted" 
depending on cllr update bits values.

/* CxLLR DMA channel x linked-list address register */
#define CLLR_LA				GENMASK(15, 2) /* Address */
#define CLLR_ULL			BIT(16) /* CxLLR update ? */
#define CLLR_UDA			BIT(27) /* CxDAR update ? */
#define CLLR_USA			BIT(28) /* CxSAR update ? */
#define CLLR_UB1			BIT(29) /* CxBR1 update ? */
#define CLLR_UT2			BIT(30) /* CxTR2 update ? */
#define CLLR_UT1			BIT(31) /* CxTR1 update ? */

If one or more CLLR_Uxx bit(s) is(are) not set, it means the 
corresponding u32 value(s) in the descriptor is(are) not there. For 
example, if CLLR_ULL bit is the only one that is set, then "cllr" value 
should be at offset 0 in linked-list data structure.

I hope this gives an insights into why I've decided not to reuse the 
existing drivers, either in whole or in part.

Amelie

>>
>>>> diff --git a/drivers/dma/stm32/stm32-dma3.c b/drivers/dma/stm32/stm32-dma3.c
>>>> new file mode 100644
>>>> index 000000000000..b5493f497d06
>>>> --- /dev/null
>>>> +++ b/drivers/dma/stm32/stm32-dma3.c
>>>> @@ -0,0 +1,1431 @@
>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>> +/*
>>>> + * STM32 DMA3 controller driver
>>>> + *
>>>> + * Copyright (C) STMicroelectronics 2024
>>>> + * Author(s): Amelie Delaunay <amelie.delaunay@foss.st.com>
>>>> + */
>>>> +
>>>> +#include <linux/bitfield.h>
>>>> +#include <linux/clk.h>
>>>> +#include <linux/dma-mapping.h>
>>>> +#include <linux/dmaengine.h>
>>>> +#include <linux/dmapool.h>
>>>> +#include <linux/init.h>
>>>> +#include <linux/iopoll.h>
>>>> +#include <linux/list.h>
>>>> +#include <linux/module.h>
>>>> +#include <linux/of_dma.h>
>>>> +#include <linux/platform_device.h>
>>>> +#include <linux/pm_runtime.h>
>>>> +#include <linux/reset.h>
>>>> +#include <linux/slab.h>
>>>> +
>>>> +#include "../virt-dma.h"
>>>> +
>>>> +#define STM32_DMA3_SECCFGR		0x00
>>>> +#define STM32_DMA3_PRIVCFGR		0x04
>>>> +#define STM32_DMA3_RCFGLOCKR		0x08
>>>> +#define STM32_DMA3_MISR			0x0C
>>>
>>> lower hex please
>>>
>>
>> Ok.
>>
>>>> +#define STM32_DMA3_SMISR		0x10
>>>> +
>>>> +#define STM32_DMA3_CLBAR(x)		(0x50 + 0x80 * (x))
>>>> +#define STM32_DMA3_CCIDCFGR(x)		(0x54 + 0x80 * (x))
>>>> +#define STM32_DMA3_CSEMCR(x)		(0x58 + 0x80 * (x))
>>>> +#define STM32_DMA3_CFCR(x)		(0x5C + 0x80 * (x))
>>>> +#define STM32_DMA3_CSR(x)		(0x60 + 0x80 * (x))
>>>> +#define STM32_DMA3_CCR(x)		(0x64 + 0x80 * (x))
>>>> +#define STM32_DMA3_CTR1(x)		(0x90 + 0x80 * (x))
>>>> +#define STM32_DMA3_CTR2(x)		(0x94 + 0x80 * (x))
>>>> +#define STM32_DMA3_CBR1(x)		(0x98 + 0x80 * (x))
>>>> +#define STM32_DMA3_CSAR(x)		(0x9C + 0x80 * (x))
>>>> +#define STM32_DMA3_CDAR(x)		(0xA0 + 0x80 * (x))
>>>> +#define STM32_DMA3_CLLR(x)		(0xCC + 0x80 * (x))
>>>> +
>>>> +#define STM32_DMA3_HWCFGR13		0xFC0 /* G_PER_CTRL(X) x=8..15 */
>>>> +#define STM32_DMA3_HWCFGR12		0xFC4 /* G_PER_CTRL(X) x=0..7 */
>>>> +#define STM32_DMA3_HWCFGR4		0xFE4 /* G_FIFO_SIZE(X) x=8..15 */
>>>> +#define STM32_DMA3_HWCFGR3		0xFE8 /* G_FIFO_SIZE(X) x=0..7 */
>>>> +#define STM32_DMA3_HWCFGR2		0xFEC /* G_MAX_REQ_ID */
>>>> +#define STM32_DMA3_HWCFGR1		0xFF0 /* G_MASTER_PORTS, G_NUM_CHANNELS, G_Mx_DATA_WIDTH */
>>>> +#define STM32_DMA3_VERR			0xFF4
>>>
>>> here as well
>>>
>>
>> Ok.
>>
>>>> +
>>>> +/* SECCFGR DMA secure configuration register */
>>>> +#define SECCFGR_SEC(x)			BIT(x)
>>>> +
>>>> +/* MISR DMA non-secure/secure masked interrupt status register */
>>>> +#define MISR_MIS(x)			BIT(x)
>>>> +
>>>> +/* CxLBAR DMA channel x linked_list base address register */
>>>> +#define CLBAR_LBA			GENMASK(31, 16)
>>>> +
>>>> +/* CxCIDCFGR DMA channel x CID register */
>>>> +#define CCIDCFGR_CFEN			BIT(0)
>>>> +#define CCIDCFGR_SEM_EN			BIT(1)
>>>> +#define CCIDCFGR_SCID			GENMASK(5, 4)
>>>> +#define CCIDCFGR_SEM_WLIST_CID0		BIT(16)
>>>> +#define CCIDCFGR_SEM_WLIST_CID1		BIT(17)
>>>> +#define CCIDCFGR_SEM_WLIST_CID2		BIT(18)
>>>> +
>>>> +enum ccidcfgr_cid {
>>>> +	CCIDCFGR_CID0,
>>>> +	CCIDCFGR_CID1,
>>>> +	CCIDCFGR_CID2,
>>>> +};
>>>> +
>>>> +/* CxSEMCR DMA channel x semaphore control register */
>>>> +#define CSEMCR_SEM_MUTEX		BIT(0)
>>>> +#define CSEMCR_SEM_CCID			GENMASK(5, 4)
>>>> +
>>>> +/* CxFCR DMA channel x flag clear register */
>>>> +#define CFCR_TCF			BIT(8)
>>>> +#define CFCR_HTF			BIT(9)
>>>> +#define CFCR_DTEF			BIT(10)
>>>> +#define CFCR_ULEF			BIT(11)
>>>> +#define CFCR_USEF			BIT(12)
>>>> +#define CFCR_SUSPF			BIT(13)
>>>> +
>>>> +/* CxSR DMA channel x status register */
>>>> +#define CSR_IDLEF			BIT(0)
>>>> +#define CSR_TCF				BIT(8)
>>>> +#define CSR_HTF				BIT(9)
>>>> +#define CSR_DTEF			BIT(10)
>>>> +#define CSR_ULEF			BIT(11)
>>>> +#define CSR_USEF			BIT(12)
>>>> +#define CSR_SUSPF			BIT(13)
>>>> +#define CSR_ALL_F			GENMASK(13, 8)
>>>> +#define CSR_FIFOL			GENMASK(24, 16)
>>>> +
>>>> +/* CxCR DMA channel x control register */
>>>> +#define CCR_EN				BIT(0)
>>>> +#define CCR_RESET			BIT(1)
>>>> +#define CCR_SUSP			BIT(2)
>>>> +#define CCR_TCIE			BIT(8)
>>>> +#define CCR_HTIE			BIT(9)
>>>> +#define CCR_DTEIE			BIT(10)
>>>> +#define CCR_ULEIE			BIT(11)
>>>> +#define CCR_USEIE			BIT(12)
>>>> +#define CCR_SUSPIE			BIT(13)
>>>> +#define CCR_ALLIE			GENMASK(13, 8)
>>>> +#define CCR_LSM				BIT(16)
>>>> +#define CCR_LAP				BIT(17)
>>>> +#define CCR_PRIO			GENMASK(23, 22)
>>>> +
>>>> +enum ccr_prio {
>>>> +	CCR_PRIO_LOW,
>>>> +	CCR_PRIO_MID,
>>>> +	CCR_PRIO_HIGH,
>>>> +	CCR_PRIO_VERY_HIGH,
>>>> +};
>>>> +
>>>> +/* CxTR1 DMA channel x transfer register 1 */
>>>> +#define CTR1_SINC			BIT(3)
>>>> +#define CTR1_SBL_1			GENMASK(9, 4)
>>>> +#define CTR1_DINC			BIT(19)
>>>> +#define CTR1_DBL_1			GENMASK(25, 20)
>>>> +#define CTR1_SDW_LOG2			GENMASK(1, 0)
>>>> +#define CTR1_PAM			GENMASK(12, 11)
>>>> +#define CTR1_SAP			BIT(14)
>>>> +#define CTR1_DDW_LOG2			GENMASK(17, 16)
>>>> +#define CTR1_DAP			BIT(30)
>>>> +
>>>> +enum ctr1_dw {
>>>> +	CTR1_DW_BYTE,
>>>> +	CTR1_DW_HWORD,
>>>> +	CTR1_DW_WORD,
>>>> +	CTR1_DW_DWORD, /* Depends on HWCFGR1.G_M0_DATA_WIDTH_ENC and .G_M1_DATA_WIDTH_ENC */
>>>> +};
>>>> +
>>>> +enum ctr1_pam {
>>>> +	CTR1_PAM_0S_LT, /* if DDW > SDW, padded with 0s else left-truncated */
>>>> +	CTR1_PAM_SE_RT, /* if DDW > SDW, sign extended else right-truncated */
>>>> +	CTR1_PAM_PACK_UNPACK, /* FIFO queued */
>>>> +};
>>>> +
>>>> +/* CxTR2 DMA channel x transfer register 2 */
>>>> +#define CTR2_REQSEL			GENMASK(7, 0)
>>>> +#define CTR2_SWREQ			BIT(9)
>>>> +#define CTR2_DREQ			BIT(10)
>>>> +#define CTR2_BREQ			BIT(11)
>>>> +#define CTR2_PFREQ			BIT(12)
>>>> +#define CTR2_TCEM			GENMASK(31, 30)
>>>> +
>>>> +enum ctr2_tcem {
>>>> +	CTR2_TCEM_BLOCK,
>>>> +	CTR2_TCEM_REPEAT_BLOCK,
>>>> +	CTR2_TCEM_LLI,
>>>> +	CTR2_TCEM_CHANNEL,
>>>> +};
>>>> +
>>>> +/* CxBR1 DMA channel x block register 1 */
>>>> +#define CBR1_BNDT			GENMASK(15, 0)
>>>> +
>>>> +/* CxLLR DMA channel x linked-list address register */
>>>> +#define CLLR_LA				GENMASK(15, 2)
>>>> +#define CLLR_ULL			BIT(16)
>>>> +#define CLLR_UDA			BIT(27)
>>>> +#define CLLR_USA			BIT(28)
>>>> +#define CLLR_UB1			BIT(29)
>>>> +#define CLLR_UT2			BIT(30)
>>>> +#define CLLR_UT1			BIT(31)
>>>> +
>>>> +/* HWCFGR13 DMA hardware configuration register 13 x=8..15 */
>>>> +/* HWCFGR12 DMA hardware configuration register 12 x=0..7 */
>>>> +#define G_PER_CTRL(x)			(ULL(0x1) << (4 * (x)))
>>>> +
>>>> +/* HWCFGR4 DMA hardware configuration register 4 x=8..15 */
>>>> +/* HWCFGR3 DMA hardware configuration register 3 x=0..7 */
>>>> +#define G_FIFO_SIZE(x)			(ULL(0x7) << (4 * (x)))
>>>> +
>>>> +#define get_chan_hwcfg(x, mask, reg)	(((reg) & (mask)) >> (4 * (x)))
>>>> +
>>>> +/* HWCFGR2 DMA hardware configuration register 2 */
>>>> +#define G_MAX_REQ_ID			GENMASK(7, 0)
>>>> +
>>>> +/* HWCFGR1 DMA hardware configuration register 1 */
>>>> +#define G_MASTER_PORTS			GENMASK(2, 0)
>>>> +#define G_NUM_CHANNELS			GENMASK(12, 8)
>>>> +#define G_M0_DATA_WIDTH_ENC		GENMASK(25, 24)
>>>> +#define G_M1_DATA_WIDTH_ENC		GENMASK(29, 28)
>>>> +
>>>> +enum stm32_dma3_master_ports {
>>>> +	AXI64, /* 1x AXI: 64-bit port 0 */
>>>> +	AHB32, /* 1x AHB: 32-bit port 0 */
>>>> +	AHB32_AHB32, /* 2x AHB: 32-bit port 0 and 32-bit port 1 */
>>>> +	AXI64_AHB32, /* 1x AXI 64-bit port 0 and 1x AHB 32-bit port 1 */
>>>> +	AXI64_AXI64, /* 2x AXI: 64-bit port 0 and 64-bit port 1 */
>>>> +	AXI128_AHB32, /* 1x AXI 128-bit port 0 and 1x AHB 32-bit port 1 */
>>>> +};
>>>> +
>>>> +enum stm32_dma3_port_data_width {
>>>> +	DW_32, /* 32-bit, for AHB */
>>>> +	DW_64, /* 64-bit, for AXI */
>>>> +	DW_128, /* 128-bit, for AXI */
>>>> +	DW_INVALID,
>>>> +};
>>>> +
>>>> +/* VERR DMA version register */
>>>> +#define VERR_MINREV			GENMASK(3, 0)
>>>> +#define VERR_MAJREV			GENMASK(7, 4)
>>>> +
>>>> +/* Device tree */
>>>> +/* struct stm32_dma3_dt_conf */
>>>> +/* .ch_conf */
>>>> +#define STM32_DMA3_DT_PRIO		GENMASK(1, 0) /* CCR_PRIO */
>>>> +#define STM32_DMA3_DT_FIFO		GENMASK(7, 4)
>>>> +/* .tr_conf */
>>>> +#define STM32_DMA3_DT_SINC		BIT(0) /* CTR1_SINC */
>>>> +#define STM32_DMA3_DT_SAP		BIT(1) /* CTR1_SAP */
>>>> +#define STM32_DMA3_DT_DINC		BIT(4) /* CTR1_DINC */
>>>> +#define STM32_DMA3_DT_DAP		BIT(5) /* CTR1_DAP */
>>>> +#define STM32_DMA3_DT_BREQ		BIT(8) /* CTR2_BREQ */
>>>> +#define STM32_DMA3_DT_PFREQ		BIT(9) /* CTR2_PFREQ */
>>>> +#define STM32_DMA3_DT_TCEM		GENMASK(13, 12) /* CTR2_TCEM */
>>>> +
>>>> +#define STM32_DMA3_MAX_BLOCK_SIZE	ALIGN_DOWN(CBR1_BNDT, 64)
>>>> +#define port_is_ahb(maxdw)		({ typeof(maxdw) (_maxdw) = (maxdw); \
>>>> +					   ((_maxdw) != DW_INVALID) && ((_maxdw) == DW_32); })
>>>> +#define port_is_axi(maxdw)		({ typeof(maxdw) (_maxdw) = (maxdw); \
>>>> +					   ((_maxdw) != DW_INVALID) && ((_maxdw) != DW_32); })
>>>> +#define get_chan_max_dw(maxdw, maxburst)((port_is_ahb(maxdw) ||			     \
>>>> +					  (maxburst) < DMA_SLAVE_BUSWIDTH_8_BYTES) ? \
>>>> +					 DMA_SLAVE_BUSWIDTH_4_BYTES : DMA_SLAVE_BUSWIDTH_8_BYTES)
>>>> +
>>>> +/* Static linked-list data structure (depends on update bits UT1/UT2/UB1/USA/UDA/ULL) */
>>>> +struct stm32_dma3_hwdesc {
>>>> +	u32 ctr1;
>>>> +	u32 ctr2;
>>>> +	u32 cbr1;
>>>> +	u32 csar;
>>>> +	u32 cdar;
>>>> +	u32 cllr;
>>>> +} __aligned(32);
>>>> +
>>>> +/*
>>>> + * CLLR_LA / sizeof(struct stm32_dma3_hwdesc) represents the number of hdwdesc that can be addressed
>>>> + * by the pointer to the next linked-list data structure. The __aligned forces the 32-byte
>>>> + * alignment. So use hardcoded 32. Multiplied by the max block size of each item, it represents
>>>> + * the sg size limitation.
>>>> + */
>>>> +#define STM32_DMA3_MAX_SEG_SIZE		((CLLR_LA / 32) * STM32_DMA3_MAX_BLOCK_SIZE)
>>>> +
>>>> +/*
>>>> + * Linked-list items
>>>> + */
>>>> +struct stm32_dma3_lli {
>>>> +	struct stm32_dma3_hwdesc *hwdesc;
>>>> +	dma_addr_t hwdesc_addr;
>>>> +};
>>>> +
>>>> +struct stm32_dma3_swdesc {
>>>> +	struct virt_dma_desc vdesc;
>>>> +	u32 ccr;
>>>> +	bool cyclic;
>>>> +	u32 lli_size;
>>>> +	struct stm32_dma3_lli lli[] __counted_by(lli_size);
>>>> +};
>>>> +
>>>> +struct stm32_dma3_dt_conf {
>>>> +	u32 ch_id;
>>>> +	u32 req_line;
>>>> +	u32 ch_conf;
>>>> +	u32 tr_conf;
>>>> +};
>>>> +
>>>> +struct stm32_dma3_chan {
>>>> +	struct virt_dma_chan vchan;
>>>> +	u32 id;
>>>> +	int irq;
>>>> +	u32 fifo_size;
>>>> +	u32 max_burst;
>>>> +	bool semaphore_mode;
>>>> +	struct stm32_dma3_dt_conf dt_config;
>>>> +	struct dma_slave_config dma_config;
>>>> +	struct dma_pool *lli_pool;
>>>> +	struct stm32_dma3_swdesc *swdesc;
>>>> +	enum ctr2_tcem tcem;
>>>> +	u32 dma_status;
>>>> +};
>>>> +
>>>> +struct stm32_dma3_ddata {
>>>> +	struct dma_device dma_dev;
>>>> +	void __iomem *base;
>>>> +	struct clk *clk;
>>>> +	struct stm32_dma3_chan *chans;
>>>> +	u32 dma_channels;
>>>> +	u32 dma_requests;
>>>> +	enum stm32_dma3_port_data_width ports_max_dw[2];
>>>> +};
>>>> +
>>>> +static inline struct stm32_dma3_ddata *to_stm32_dma3_ddata(struct stm32_dma3_chan *chan)
>>>> +{
>>>> +	return container_of(chan->vchan.chan.device, struct stm32_dma3_ddata, dma_dev);
>>>> +}
>>>> +
>>>> +static inline struct stm32_dma3_chan *to_stm32_dma3_chan(struct dma_chan *c)
>>>> +{
>>>> +	return container_of(c, struct stm32_dma3_chan, vchan.chan);
>>>> +}
>>>> +
>>>> +static inline struct stm32_dma3_swdesc *to_stm32_dma3_swdesc(struct virt_dma_desc *vdesc)
>>>> +{
>>>> +	return container_of(vdesc, struct stm32_dma3_swdesc, vdesc);
>>>> +}
>>>> +
>>>> +static struct device *chan2dev(struct stm32_dma3_chan *chan)
>>>> +{
>>>> +	return &chan->vchan.chan.dev->device;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_chan_dump_reg(struct stm32_dma3_chan *chan)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	struct device *dev = chan2dev(chan);
>>>> +	u32 id = chan->id, offset;
>>>> +
>>>> +	offset = STM32_DMA3_SECCFGR;
>>>> +	dev_dbg(dev, "SECCFGR(0x%03x): %08x\n", offset, readl_relaxed(ddata->base + offset));
>>>> +	offset = STM32_DMA3_PRIVCFGR;
>>>> +	dev_dbg(dev, "PRIVCFGR(0x%03x): %08x\n", offset, readl_relaxed(ddata->base + offset));
>>>> +	offset = STM32_DMA3_CCIDCFGR(id);
>>>> +	dev_dbg(dev, "C%dCIDCFGR(0x%03x): %08x\n", id, offset, readl_relaxed(ddata->base + offset));
>>>> +	offset = STM32_DMA3_CSEMCR(id);
>>>> +	dev_dbg(dev, "C%dSEMCR(0x%03x): %08x\n", id, offset, readl_relaxed(ddata->base + offset));
>>>> +	offset = STM32_DMA3_CSR(id);
>>>> +	dev_dbg(dev, "C%dSR(0x%03x): %08x\n", id, offset, readl_relaxed(ddata->base + offset));
>>>> +	offset = STM32_DMA3_CCR(id);
>>>> +	dev_dbg(dev, "C%dCR(0x%03x): %08x\n", id, offset, readl_relaxed(ddata->base + offset));
>>>> +	offset = STM32_DMA3_CTR1(id);
>>>> +	dev_dbg(dev, "C%dTR1(0x%03x): %08x\n", id, offset, readl_relaxed(ddata->base + offset));
>>>> +	offset = STM32_DMA3_CTR2(id);
>>>> +	dev_dbg(dev, "C%dTR2(0x%03x): %08x\n", id, offset, readl_relaxed(ddata->base + offset));
>>>> +	offset = STM32_DMA3_CBR1(id);
>>>> +	dev_dbg(dev, "C%dBR1(0x%03x): %08x\n", id, offset, readl_relaxed(ddata->base + offset));
>>>> +	offset = STM32_DMA3_CSAR(id);
>>>> +	dev_dbg(dev, "C%dSAR(0x%03x): %08x\n", id, offset, readl_relaxed(ddata->base + offset));
>>>> +	offset = STM32_DMA3_CDAR(id);
>>>> +	dev_dbg(dev, "C%dDAR(0x%03x): %08x\n", id, offset, readl_relaxed(ddata->base + offset));
>>>> +	offset = STM32_DMA3_CLLR(id);
>>>> +	dev_dbg(dev, "C%dLLR(0x%03x): %08x\n", id, offset, readl_relaxed(ddata->base + offset));
>>>> +	offset = STM32_DMA3_CLBAR(id);
>>>> +	dev_dbg(dev, "C%dLBAR(0x%03x): %08x\n", id, offset, readl_relaxed(ddata->base + offset));
>>>> +}
>>>> +
>>>> +static void stm32_dma3_chan_dump_hwdesc(struct stm32_dma3_chan *chan,
>>>> +					struct stm32_dma3_swdesc *swdesc)
>>>> +{
>>>> +	struct stm32_dma3_hwdesc *hwdesc;
>>>> +	int i;
>>>> +
>>>> +	for (i = 0; i < swdesc->lli_size; i++) {
>>>> +		hwdesc = swdesc->lli[i].hwdesc;
>>>> +		if (i)
>>>> +			dev_dbg(chan2dev(chan), "V\n");
>>>> +		dev_dbg(chan2dev(chan), "[%d]@%pad\n", i, &swdesc->lli[i].hwdesc_addr);
>>>> +		dev_dbg(chan2dev(chan), "| C%dTR1: %08x\n", chan->id, hwdesc->ctr1);
>>>> +		dev_dbg(chan2dev(chan), "| C%dTR2: %08x\n", chan->id, hwdesc->ctr2);
>>>> +		dev_dbg(chan2dev(chan), "| C%dBR1: %08x\n", chan->id, hwdesc->cbr1);
>>>> +		dev_dbg(chan2dev(chan), "| C%dSAR: %08x\n", chan->id, hwdesc->csar);
>>>> +		dev_dbg(chan2dev(chan), "| C%dDAR: %08x\n", chan->id, hwdesc->cdar);
>>>> +		dev_dbg(chan2dev(chan), "| C%dLLR: %08x\n", chan->id, hwdesc->cllr);
>>>> +	}
>>>> +
>>>> +	if (swdesc->cyclic) {
>>>> +		dev_dbg(chan2dev(chan), "|\n");
>>>> +		dev_dbg(chan2dev(chan), "-->[0]@%pad\n", &swdesc->lli[0].hwdesc_addr);
>>>> +	} else {
>>>> +		dev_dbg(chan2dev(chan), "X\n");
>>>> +	}
>>>> +}
>>>> +
>>>> +static struct stm32_dma3_swdesc *stm32_dma3_chan_desc_alloc(struct stm32_dma3_chan *chan, u32 count)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	struct stm32_dma3_swdesc *swdesc;
>>>> +	int i;
>>>> +
>>>> +	/*
>>>> +	 * If the memory to be allocated for the number of hwdesc (6 u32 members but 32-bytes
>>>> +	 * aligned) is greater than the maximum address of CLLR_LA, then the last items can't be
>>>> +	 * addressed, so abort the allocation.
>>>> +	 */
>>>> +	if ((count * 32) > CLLR_LA) {
>>>> +		dev_err(chan2dev(chan), "Transfer is too big (> %luB)\n", STM32_DMA3_MAX_SEG_SIZE);
>>>> +		return NULL;
>>>> +	}
>>>> +
>>>> +	swdesc = kzalloc(struct_size(swdesc, lli, count), GFP_NOWAIT);
>>>> +	if (!swdesc)
>>>> +		return NULL;
>>>> +
>>>> +	for (i = 0; i < count; i++) {
>>>> +		swdesc->lli[i].hwdesc = dma_pool_zalloc(chan->lli_pool, GFP_NOWAIT,
>>>> +							&swdesc->lli[i].hwdesc_addr);
>>>> +		if (!swdesc->lli[i].hwdesc)
>>>> +			goto err_pool_free;
>>>> +	}
>>>> +	swdesc->lli_size = count;
>>>> +	swdesc->ccr = 0;
>>>> +
>>>> +	/* Set LL base address */
>>>> +	writel_relaxed(swdesc->lli[0].hwdesc_addr & CLBAR_LBA,
>>>> +		       ddata->base + STM32_DMA3_CLBAR(chan->id));
>>>> +
>>>> +	/* Set LL allocated port */
>>>> +	swdesc->ccr &= ~CCR_LAP;
>>>> +
>>>> +	return swdesc;
>>>> +
>>>> +err_pool_free:
>>>> +	dev_err(chan2dev(chan), "Failed to alloc descriptors\n");
>>>> +	while (--i >= 0)
>>>> +		dma_pool_free(chan->lli_pool, swdesc->lli[i].hwdesc, swdesc->lli[i].hwdesc_addr);
>>>> +	kfree(swdesc);
>>>> +
>>>> +	return NULL;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_chan_desc_free(struct stm32_dma3_chan *chan,
>>>> +				      struct stm32_dma3_swdesc *swdesc)
>>>> +{
>>>> +	int i;
>>>> +
>>>> +	for (i = 0; i < swdesc->lli_size; i++)
>>>> +		dma_pool_free(chan->lli_pool, swdesc->lli[i].hwdesc, swdesc->lli[i].hwdesc_addr);
>>>> +
>>>> +	kfree(swdesc);
>>>> +}
>>>> +
>>>> +static void stm32_dma3_chan_vdesc_free(struct virt_dma_desc *vdesc)
>>>> +{
>>>> +	struct stm32_dma3_swdesc *swdesc = to_stm32_dma3_swdesc(vdesc);
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(vdesc->tx.chan);
>>>> +
>>>> +	stm32_dma3_chan_desc_free(chan, swdesc);
>>>> +}
>>>> +
>>>> +static void stm32_dma3_check_user_setting(struct stm32_dma3_chan *chan)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	struct device *dev = chan2dev(chan);
>>>> +	u32 ctr1 = readl_relaxed(ddata->base + STM32_DMA3_CTR1(chan->id));
>>>> +	u32 cbr1 = readl_relaxed(ddata->base + STM32_DMA3_CBR1(chan->id));
>>>> +	u32 csar = readl_relaxed(ddata->base + STM32_DMA3_CSAR(chan->id));
>>>> +	u32 cdar = readl_relaxed(ddata->base + STM32_DMA3_CDAR(chan->id));
>>>> +	u32 cllr = readl_relaxed(ddata->base + STM32_DMA3_CLLR(chan->id));
>>>> +	u32 bndt = FIELD_GET(CBR1_BNDT, cbr1);
>>>> +	u32 sdw = 1 << FIELD_GET(CTR1_SDW_LOG2, ctr1);
>>>> +	u32 ddw = 1 << FIELD_GET(CTR1_DDW_LOG2, ctr1);
>>>> +	u32 sap = FIELD_GET(CTR1_SAP, ctr1);
>>>> +	u32 dap = FIELD_GET(CTR1_DAP, ctr1);
>>>> +
>>>> +	if (!bndt && !FIELD_GET(CLLR_UB1, cllr))
>>>> +		dev_err(dev, "null source block size and no update of this value\n");
>>>> +	if (bndt % sdw)
>>>> +		dev_err(dev, "source block size not multiple of src data width\n");
>>>> +	if (FIELD_GET(CTR1_PAM, ctr1) == CTR1_PAM_PACK_UNPACK && bndt % ddw)
>>>> +		dev_err(dev, "(un)packing mode w/ src block size not multiple of dst data width\n");
>>>> +	if (csar % sdw)
>>>> +		dev_err(dev, "unaligned source address not multiple of src data width\n");
>>>> +	if (cdar % ddw)
>>>> +		dev_err(dev, "unaligned destination address not multiple of dst data width\n");
>>>> +	if (sdw == DMA_SLAVE_BUSWIDTH_8_BYTES && port_is_ahb(ddata->ports_max_dw[sap]))
>>>> +		dev_err(dev, "double-word source data width not supported on port %u\n", sap);
>>>> +	if (ddw == DMA_SLAVE_BUSWIDTH_8_BYTES && port_is_ahb(ddata->ports_max_dw[dap]))
>>>> +		dev_err(dev, "double-word destination data width not supported on port %u\n", dap);
>>>
>>> NO error/abort if this is wrong...?
>>>
>>
>> User setting error triggers an interrupt caught in stm32_dma3_chan_irq()
>> interrupt handler.
>> Indeed User setting error can occur when enabling the channel or when DMA3
>> registers are updated with each linked-list item.
>> In interrupt handler, when USEF (User Setting Error Flag) is set, this
>> function (stm32_dma3_check_user_setting) helps the user to understand what
>> went wrong. The hardware automatically disables the channel to prevent the
>> execution of the wrongly programmed transfer and the driver resets the
>> channel and sets chan->dma_status = DMA_ERROR;. dmaengine_tx_status() will
>> return DMA_ERROR.
>> So from user point of view, the transfer will never complete, and the
>> channel is ready to be reprogrammed.
>> Note that in _prep_ functions, all is checked to avoid user setting error.
>> If a user setting error occurs, it is rather due to a corrupted linked-list
>> item (that should fortunately never happen).
>>
>>>> +}
>>>> +
>>>> +static void stm32_dma3_chan_prep_hwdesc(struct stm32_dma3_chan *chan,
>>>> +					struct stm32_dma3_swdesc *swdesc,
>>>> +					u32 curr, dma_addr_t src, dma_addr_t dst, u32 len,
>>>> +					u32 ctr1, u32 ctr2, bool is_last, bool is_cyclic)
>>>> +{
>>>> +	struct stm32_dma3_hwdesc *hwdesc;
>>>> +	dma_addr_t next_lli;
>>>> +	u32 next = curr + 1;
>>>> +
>>>> +	hwdesc = swdesc->lli[curr].hwdesc;
>>>> +	hwdesc->ctr1 = ctr1;
>>>> +	hwdesc->ctr2 = ctr2;
>>>> +	hwdesc->cbr1 = FIELD_PREP(CBR1_BNDT, len);
>>>> +	hwdesc->csar = src;
>>>> +	hwdesc->cdar = dst;
>>>> +
>>>> +	if (is_last) {
>>>> +		if (is_cyclic)
>>>> +			next_lli = swdesc->lli[0].hwdesc_addr;
>>>> +		else
>>>> +			next_lli = 0;
>>>> +	} else {
>>>> +		next_lli = swdesc->lli[next].hwdesc_addr;
>>>> +	}
>>>> +
>>>> +	hwdesc->cllr = 0;
>>>> +	if (next_lli) {
>>>> +		hwdesc->cllr |= CLLR_UT1 | CLLR_UT2 | CLLR_UB1;
>>>> +		hwdesc->cllr |= CLLR_USA | CLLR_UDA | CLLR_ULL;
>>>> +		hwdesc->cllr |= (next_lli & CLLR_LA);
>>>> +	}
>>>> +}
>>>> +
>>>> +static enum dma_slave_buswidth stm32_dma3_get_max_dw(u32 chan_max_burst,
>>>> +						     enum stm32_dma3_port_data_width port_max_dw,
>>>> +						     u32 len, dma_addr_t addr)
>>>> +{
>>>> +	enum dma_slave_buswidth max_dw = get_chan_max_dw(port_max_dw, chan_max_burst);
>>>> +
>>>> +	/* len and addr must be a multiple of dw */
>>>> +	return 1 << __ffs(len | addr | max_dw);
>>>> +}
>>>> +
>>>> +static u32 stm32_dma3_get_max_burst(u32 len, enum dma_slave_buswidth dw, u32 chan_max_burst)
>>>> +{
>>>> +	u32 max_burst = chan_max_burst ? chan_max_burst / dw : 1;
>>>> +
>>>> +	/* len is a multiple of dw, so if len is < chan_max_burst, shorten burst */
>>>> +	if (len < chan_max_burst)
>>>> +		max_burst = len / dw;
>>>> +
>>>> +	/*
>>>> +	 * HW doesn't modify the burst if burst size <= half of the fifo size.
>>>> +	 * If len is not a multiple of burst size, last burst is shortened by HW.
>>>> +	 */
>>>> +	return max_burst;
>>>> +}
>>>> +
>>>> +static int stm32_dma3_chan_prep_hw(struct stm32_dma3_chan *chan, enum dma_transfer_direction dir,
>>>> +				   u32 *ccr, u32 *ctr1, u32 *ctr2,
>>>> +				   dma_addr_t src_addr, dma_addr_t dst_addr, u32 len)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	struct dma_device dma_device = ddata->dma_dev;
>>>> +	u32 sdw, ddw, sbl_max, dbl_max, tcem;
>>>> +	u32 _ctr1 = 0, _ctr2 = 0;
>>>> +	u32 ch_conf = chan->dt_config.ch_conf;
>>>> +	u32 tr_conf = chan->dt_config.tr_conf;
>>>> +	u32 sap = FIELD_GET(STM32_DMA3_DT_SAP, tr_conf), sap_max_dw;
>>>> +	u32 dap = FIELD_GET(STM32_DMA3_DT_DAP, tr_conf), dap_max_dw;
>>>> +
>>>> +	dev_dbg(chan2dev(chan), "%s from %pad to %pad\n",
>>>> +		dmaengine_get_direction_text(dir), &src_addr, &dst_addr);
>>>> +
>>>> +	sdw = chan->dma_config.src_addr_width ? : get_chan_max_dw(sap, chan->max_burst);
>>>> +	ddw = chan->dma_config.dst_addr_width ? : get_chan_max_dw(dap, chan->max_burst);
>>>> +	sbl_max = chan->dma_config.src_maxburst ? : 1;
>>>> +	dbl_max = chan->dma_config.dst_maxburst ? : 1;
>>>> +
>>>> +	/* Following conditions would raise User Setting Error interrupt */
>>>> +	if (!(dma_device.src_addr_widths & BIT(sdw)) || !(dma_device.dst_addr_widths & BIT(ddw))) {
>>>> +		dev_err(chan2dev(chan), "Bus width (src=%u, dst=%u) not supported\n", sdw, ddw);
>>>> +		return -EINVAL;
>>>> +	}
>>>> +
>>>> +	if (ddata->ports_max_dw[1] == DW_INVALID && (sap || dap)) {
>>>> +		dev_err(chan2dev(chan), "Only one master port, port 1 is not supported\n");
>>>> +		return -EINVAL;
>>>> +	}
>>>> +
>>>> +	sap_max_dw = ddata->ports_max_dw[sap];
>>>> +	dap_max_dw = ddata->ports_max_dw[dap];
>>>> +	if ((port_is_ahb(sap_max_dw) && sdw == DMA_SLAVE_BUSWIDTH_8_BYTES) ||
>>>> +	    (port_is_ahb(dap_max_dw) && ddw == DMA_SLAVE_BUSWIDTH_8_BYTES)) {
>>>> +		dev_err(chan2dev(chan),
>>>> +			"8 bytes buswidth (src=%u, dst=%u) not supported on port (sap=%u, dap=%u\n",
>>>> +			sdw, ddw, sap, dap);
>>>> +		return -EINVAL;
>>>> +	}
>>>> +
>>>> +	if (FIELD_GET(STM32_DMA3_DT_SINC, tr_conf))
>>>> +		_ctr1 |= CTR1_SINC;
>>>> +	if (sap)
>>>> +		_ctr1 |= CTR1_SAP;
>>>> +	if (FIELD_GET(STM32_DMA3_DT_DINC, tr_conf))
>>>> +		_ctr1 |= CTR1_DINC;
>>>> +	if (dap)
>>>> +		_ctr1 |= CTR1_DAP;
>>>> +
>>>> +	_ctr2 |= FIELD_PREP(CTR2_REQSEL, chan->dt_config.req_line) & ~CTR2_SWREQ;
>>>> +	if (FIELD_GET(STM32_DMA3_DT_BREQ, tr_conf))
>>>> +		_ctr2 |= CTR2_BREQ;
>>>> +	if (dir == DMA_DEV_TO_MEM && FIELD_GET(STM32_DMA3_DT_PFREQ, tr_conf))
>>>> +		_ctr2 |= CTR2_PFREQ;
>>>> +	tcem = FIELD_GET(STM32_DMA3_DT_TCEM, tr_conf);
>>>> +	_ctr2 |= FIELD_PREP(CTR2_TCEM, tcem);
>>>> +
>>>> +	/* Store TCEM to know on which event TC flag occurred */
>>>> +	chan->tcem = tcem;
>>>> +	/* Store direction for residue computation */
>>>> +	chan->dma_config.direction = dir;
>>>> +
>>>> +	switch (dir) {
>>>> +	case DMA_MEM_TO_DEV:
>>>> +		/* Set destination (device) data width and burst */
>>>> +		ddw = min_t(u32, ddw, stm32_dma3_get_max_dw(chan->max_burst, dap_max_dw,
>>>> +							    len, dst_addr));
>>>> +		dbl_max = min_t(u32, dbl_max, stm32_dma3_get_max_burst(len, ddw, chan->max_burst));
>>>> +
>>>> +		/* Set source (memory) data width and burst */
>>>> +		sdw = stm32_dma3_get_max_dw(chan->max_burst, sap_max_dw, len, src_addr);
>>>> +		sbl_max = stm32_dma3_get_max_burst(len, sdw, chan->max_burst);
>>>> +
>>>> +		_ctr1 |= FIELD_PREP(CTR1_SDW_LOG2, ilog2(sdw));
>>>> +		_ctr1 |= FIELD_PREP(CTR1_SBL_1, sbl_max - 1);
>>>> +		_ctr1 |= FIELD_PREP(CTR1_DDW_LOG2, ilog2(ddw));
>>>> +		_ctr1 |= FIELD_PREP(CTR1_DBL_1, dbl_max - 1);
>>>> +
>>>> +		if (ddw != sdw) {
>>>> +			_ctr1 |= FIELD_PREP(CTR1_PAM, CTR1_PAM_PACK_UNPACK);
>>>> +			/* Should never reach this case as ddw is clamped down */
>>>> +			if (len & (ddw - 1)) {
>>>> +				dev_err(chan2dev(chan),
>>>> +					"Packing mode is enabled and len is not multiple of ddw");
>>>> +				return -EINVAL;
>>>> +			}
>>>> +		}
>>>> +
>>>> +		/* dst = dev */
>>>> +		_ctr2 |= CTR2_DREQ;
>>>> +
>>>> +		break;
>>>> +
>>>> +	case DMA_DEV_TO_MEM:
>>>> +		/* Set source (device) data width and burst */
>>>> +		sdw = min_t(u32, sdw, stm32_dma3_get_max_dw(chan->max_burst, sap_max_dw,
>>>> +							    len, src_addr));
>>>> +		sbl_max = min_t(u32, sbl_max, stm32_dma3_get_max_burst(len, sdw, chan->max_burst));
>>>> +
>>>> +		/* Set destination (memory) data width and burst */
>>>> +		ddw = stm32_dma3_get_max_dw(chan->max_burst, dap_max_dw, len, dst_addr);
>>>> +		dbl_max = stm32_dma3_get_max_burst(len, ddw, chan->max_burst);
>>>> +
>>>> +		_ctr1 |= FIELD_PREP(CTR1_SDW_LOG2, ilog2(sdw));
>>>> +		_ctr1 |= FIELD_PREP(CTR1_SBL_1, sbl_max - 1);
>>>> +		_ctr1 |= FIELD_PREP(CTR1_DDW_LOG2, ilog2(ddw));
>>>> +		_ctr1 |= FIELD_PREP(CTR1_DBL_1, dbl_max - 1);
>>>> +
>>>> +		if (ddw != sdw) {
>>>> +			_ctr1 |= FIELD_PREP(CTR1_PAM, CTR1_PAM_PACK_UNPACK);
>>>> +			/* Should never reach this case as ddw is clamped down */
>>>> +			if (len & (ddw - 1)) {
>>>> +				dev_err(chan2dev(chan),
>>>> +					"Packing mode is enabled and len is not multiple of ddw\n");
>>>> +				return -EINVAL;
>>>> +			}
>>>> +		}
>>>> +
>>>> +		/* dst = mem */
>>>> +		_ctr2 &= ~CTR2_DREQ;
>>>> +
>>>> +		break;
>>>> +
>>>> +	default:
>>>> +		dev_err(chan2dev(chan), "Direction %s not supported\n",
>>>> +			dmaengine_get_direction_text(dir));
>>>> +		return -EINVAL;
>>>> +	}
>>>> +
>>>> +	*ccr |= FIELD_PREP(CCR_PRIO, FIELD_GET(STM32_DMA3_DT_PRIO, ch_conf));
>>>> +	*ctr1 = _ctr1;
>>>> +	*ctr2 = _ctr2;
>>>> +
>>>> +	dev_dbg(chan2dev(chan), "%s: sdw=%u bytes sbl=%u beats ddw=%u bytes dbl=%u beats\n",
>>>> +		__func__, sdw, sbl_max, ddw, dbl_max);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_chan_start(struct stm32_dma3_chan *chan)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	struct virt_dma_desc *vdesc;
>>>> +	struct stm32_dma3_hwdesc *hwdesc;
>>>> +	u32 id = chan->id;
>>>> +	u32 csr, ccr;
>>>> +
>>>> +	vdesc = vchan_next_desc(&chan->vchan);
>>>> +	if (!vdesc) {
>>>> +		chan->swdesc = NULL;
>>>> +		return;
>>>> +	}
>>>> +	list_del(&vdesc->node);
>>>> +
>>>> +	chan->swdesc = to_stm32_dma3_swdesc(vdesc);
>>>> +	hwdesc = chan->swdesc->lli[0].hwdesc;
>>>> +
>>>> +	stm32_dma3_chan_dump_hwdesc(chan, chan->swdesc);
>>>> +
>>>> +	writel_relaxed(chan->swdesc->ccr, ddata->base + STM32_DMA3_CCR(id));
>>>> +	writel_relaxed(hwdesc->ctr1, ddata->base + STM32_DMA3_CTR1(id));
>>>> +	writel_relaxed(hwdesc->ctr2, ddata->base + STM32_DMA3_CTR2(id));
>>>> +	writel_relaxed(hwdesc->cbr1, ddata->base + STM32_DMA3_CBR1(id));
>>>> +	writel_relaxed(hwdesc->csar, ddata->base + STM32_DMA3_CSAR(id));
>>>> +	writel_relaxed(hwdesc->cdar, ddata->base + STM32_DMA3_CDAR(id));
>>>> +	writel_relaxed(hwdesc->cllr, ddata->base + STM32_DMA3_CLLR(id));
>>>> +
>>>> +	/* Clear any pending interrupts */
>>>> +	csr = readl_relaxed(ddata->base + STM32_DMA3_CSR(id));
>>>> +	if (csr & CSR_ALL_F)
>>>> +		writel_relaxed(csr, ddata->base + STM32_DMA3_CFCR(id));
>>>> +
>>>> +	stm32_dma3_chan_dump_reg(chan);
>>>> +
>>>> +	ccr = readl_relaxed(ddata->base + STM32_DMA3_CCR(id));
>>>> +	writel_relaxed(ccr | CCR_EN, ddata->base + STM32_DMA3_CCR(id));
>>>> +
>>>> +	chan->dma_status = DMA_IN_PROGRESS;
>>>> +
>>>> +	dev_dbg(chan2dev(chan), "vchan %pK: started\n", &chan->vchan);
>>>> +}
>>>> +
>>>> +static int stm32_dma3_chan_suspend(struct stm32_dma3_chan *chan, bool susp)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	u32 csr, ccr = readl_relaxed(ddata->base + STM32_DMA3_CCR(chan->id)) & ~CCR_EN;
>>>> +	int ret = 0;
>>>> +
>>>> +	if (susp)
>>>> +		ccr |= CCR_SUSP;
>>>> +	else
>>>> +		ccr &= ~CCR_SUSP;
>>>> +
>>>> +	writel_relaxed(ccr, ddata->base + STM32_DMA3_CCR(chan->id));
>>>> +
>>>> +	if (susp) {
>>>> +		ret = readl_relaxed_poll_timeout_atomic(ddata->base + STM32_DMA3_CSR(chan->id), csr,
>>>> +							csr & CSR_SUSPF, 1, 10);
>>>> +		if (!ret)
>>>> +			writel_relaxed(CFCR_SUSPF, ddata->base + STM32_DMA3_CFCR(chan->id));
>>>> +
>>>> +		stm32_dma3_chan_dump_reg(chan);
>>>> +	}
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_chan_reset(struct stm32_dma3_chan *chan)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	u32 ccr = readl_relaxed(ddata->base + STM32_DMA3_CCR(chan->id)) & ~CCR_EN;
>>>> +
>>>> +	writel_relaxed(ccr |= CCR_RESET, ddata->base + STM32_DMA3_CCR(chan->id));
>>>> +}
>>>> +
>>>> +static int stm32_dma3_chan_stop(struct stm32_dma3_chan *chan)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	u32 ccr;
>>>> +	int ret = 0;
>>>> +
>>>> +	chan->dma_status = DMA_COMPLETE;
>>>> +
>>>> +	/* Disable interrupts */
>>>> +	ccr = readl_relaxed(ddata->base + STM32_DMA3_CCR(chan->id));
>>>> +	writel_relaxed(ccr & ~(CCR_ALLIE | CCR_EN), ddata->base + STM32_DMA3_CCR(chan->id));
>>>> +
>>>> +	if (!(ccr & CCR_SUSP) && (ccr & CCR_EN)) {
>>>> +		/* Suspend the channel */
>>>> +		ret = stm32_dma3_chan_suspend(chan, true);
>>>> +		if (ret)
>>>> +			dev_warn(chan2dev(chan), "%s: timeout, data might be lost\n", __func__);
>>>> +	}
>>>> +
>>>> +	/*
>>>> +	 * Reset the channel: this causes the reset of the FIFO and the reset of the channel
>>>> +	 * internal state, the reset of CCR_EN and CCR_SUSP bits.
>>>> +	 */
>>>> +	stm32_dma3_chan_reset(chan);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_chan_complete(struct stm32_dma3_chan *chan)
>>>> +{
>>>> +	if (!chan->swdesc)
>>>> +		return;
>>>> +
>>>> +	vchan_cookie_complete(&chan->swdesc->vdesc);
>>>> +	chan->swdesc = NULL;
>>>> +	stm32_dma3_chan_start(chan);
>>>> +}
>>>> +
>>>> +static irqreturn_t stm32_dma3_chan_irq(int irq, void *devid)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = devid;
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	u32 misr, csr, ccr;
>>>> +
>>>> +	spin_lock(&chan->vchan.lock);
>>>> +
>>>> +	misr = readl_relaxed(ddata->base + STM32_DMA3_MISR);
>>>> +	if (!(misr & MISR_MIS(chan->id))) {
>>>> +		spin_unlock(&chan->vchan.lock);
>>>> +		return IRQ_NONE;
>>>> +	}
>>>> +
>>>> +	csr = readl_relaxed(ddata->base + STM32_DMA3_CSR(chan->id));
>>>> +	ccr = readl_relaxed(ddata->base + STM32_DMA3_CCR(chan->id)) & CCR_ALLIE;
>>>> +
>>>> +	if (csr & CSR_TCF && ccr & CCR_TCIE) {
>>>> +		if (chan->swdesc->cyclic)
>>>> +			vchan_cyclic_callback(&chan->swdesc->vdesc);
>>>> +		else
>>>> +			stm32_dma3_chan_complete(chan);
>>>> +	}
>>>> +
>>>> +	if (csr & CSR_USEF && ccr & CCR_USEIE) {
>>>> +		dev_err(chan2dev(chan), "User setting error\n");
>>>> +		chan->dma_status = DMA_ERROR;
>>>> +		/* CCR.EN automatically cleared by HW */
>>>> +		stm32_dma3_check_user_setting(chan);
>>>> +		stm32_dma3_chan_reset(chan);
>>>> +	}
>>>> +
>>>> +	if (csr & CSR_ULEF && ccr & CCR_ULEIE) {
>>>> +		dev_err(chan2dev(chan), "Update link transfer error\n");
>>>> +		chan->dma_status = DMA_ERROR;
>>>> +		/* CCR.EN automatically cleared by HW */
>>>> +		stm32_dma3_chan_reset(chan);
>>>> +	}
>>>> +
>>>> +	if (csr & CSR_DTEF && ccr & CCR_DTEIE) {
>>>> +		dev_err(chan2dev(chan), "Data transfer error\n");
>>>> +		chan->dma_status = DMA_ERROR;
>>>> +		/* CCR.EN automatically cleared by HW */
>>>> +		stm32_dma3_chan_reset(chan);
>>>> +	}
>>>> +
>>>> +	/*
>>>> +	 * Half Transfer Interrupt may be disabled but Half Transfer Flag can be set,
>>>> +	 * ensure HTF flag to be cleared, with other flags.
>>>> +	 */
>>>> +	csr &= (ccr | CCR_HTIE);
>>>> +
>>>> +	if (csr)
>>>> +		writel_relaxed(csr, ddata->base + STM32_DMA3_CFCR(chan->id));
>>>> +
>>>> +	spin_unlock(&chan->vchan.lock);
>>>> +
>>>> +	return IRQ_HANDLED;
>>>> +}
>>>> +
>>>> +static int stm32_dma3_alloc_chan_resources(struct dma_chan *c)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	u32 id = chan->id, csemcr, ccid;
>>>> +	int ret;
>>>> +
>>>> +	ret = pm_runtime_resume_and_get(ddata->dma_dev.dev);
>>>> +	if (ret < 0)
>>>> +		return ret;
>>>> +
>>>> +	/* Ensure the channel is free */
>>>> +	if (chan->semaphore_mode &&
>>>> +	    readl_relaxed(ddata->base + STM32_DMA3_CSEMCR(chan->id)) & CSEMCR_SEM_MUTEX) {
>>>> +		ret = -EBUSY;
>>>> +		goto err_put_sync;
>>>> +	}
>>>> +
>>>> +	chan->lli_pool = dmam_pool_create(dev_name(&c->dev->device), c->device->dev,
>>>> +					  sizeof(struct stm32_dma3_hwdesc),
>>>> +					  __alignof__(struct stm32_dma3_hwdesc), 0);
>>>> +	if (!chan->lli_pool) {
>>>> +		dev_err(chan2dev(chan), "Failed to create LLI pool\n");
>>>> +		ret = -ENOMEM;
>>>> +		goto err_put_sync;
>>>> +	}
>>>> +
>>>> +	/* Take the channel semaphore */
>>>> +	if (chan->semaphore_mode) {
>>>> +		writel_relaxed(CSEMCR_SEM_MUTEX, ddata->base + STM32_DMA3_CSEMCR(id));
>>>> +		csemcr = readl_relaxed(ddata->base + STM32_DMA3_CSEMCR(id));
>>>> +		ccid = FIELD_GET(CSEMCR_SEM_CCID, csemcr);
>>>> +		/* Check that the channel is well taken */
>>>> +		if (ccid != CCIDCFGR_CID1) {
>>>> +			dev_err(chan2dev(chan), "Not under CID1 control (in-use by CID%d)\n", ccid);
>>>> +			ret = -EPERM;
>>>> +			goto err_pool_destroy;
>>>> +		}
>>>> +		dev_dbg(chan2dev(chan), "Under CID1 control (semcr=0x%08x)\n", csemcr);
>>>> +	}
>>>> +
>>>> +	return 0;
>>>> +
>>>> +err_pool_destroy:
>>>> +	dmam_pool_destroy(chan->lli_pool);
>>>> +	chan->lli_pool = NULL;
>>>> +
>>>> +err_put_sync:
>>>> +	pm_runtime_put_sync(ddata->dma_dev.dev);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_free_chan_resources(struct dma_chan *c)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	unsigned long flags;
>>>> +
>>>> +	/* Ensure channel is in idle state */
>>>> +	spin_lock_irqsave(&chan->vchan.lock, flags);
>>>> +	stm32_dma3_chan_stop(chan);
>>>> +	chan->swdesc = NULL;
>>>> +	spin_unlock_irqrestore(&chan->vchan.lock, flags);
>>>> +
>>>> +	vchan_free_chan_resources(to_virt_chan(c));
>>>> +
>>>> +	dmam_pool_destroy(chan->lli_pool);
>>>> +	chan->lli_pool = NULL;
>>>> +
>>>> +	/* Release the channel semaphore */
>>>> +	if (chan->semaphore_mode)
>>>> +		writel_relaxed(0, ddata->base + STM32_DMA3_CSEMCR(chan->id));
>>>> +
>>>> +	pm_runtime_put_sync(ddata->dma_dev.dev);
>>>> +
>>>> +	/* Reset configuration */
>>>> +	memset(&chan->dt_config, 0, sizeof(chan->dt_config));
>>>> +	memset(&chan->dma_config, 0, sizeof(chan->dma_config));
>>>> +}
>>>> +
>>>> +static struct dma_async_tx_descriptor *stm32_dma3_prep_slave_sg(struct dma_chan *c,
>>>> +								struct scatterlist *sgl,
>>>> +								unsigned int sg_len,
>>>> +								enum dma_transfer_direction dir,
>>>> +								unsigned long flags, void *context)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +	struct stm32_dma3_swdesc *swdesc;
>>>> +	struct scatterlist *sg;
>>>> +	size_t len;
>>>> +	dma_addr_t sg_addr, dev_addr, src, dst;
>>>> +	u32 i, j, count, ctr1, ctr2;
>>>> +	int ret;
>>>> +
>>>> +	count = sg_len;
>>>> +	for_each_sg(sgl, sg, sg_len, i) {
>>>> +		len = sg_dma_len(sg);
>>>> +		if (len > STM32_DMA3_MAX_BLOCK_SIZE)
>>>> +			count += DIV_ROUND_UP(len, STM32_DMA3_MAX_BLOCK_SIZE) - 1;
>>>> +	}
>>>> +
>>>> +	swdesc = stm32_dma3_chan_desc_alloc(chan, count);
>>>> +	if (!swdesc)
>>>> +		return NULL;
>>>> +
>>>> +	/* sg_len and i correspond to the initial sgl; count and j correspond to the hwdesc LL */
>>>> +	j = 0;
>>>> +	for_each_sg(sgl, sg, sg_len, i) {
>>>> +		sg_addr = sg_dma_address(sg);
>>>> +		dev_addr = (dir == DMA_MEM_TO_DEV) ? chan->dma_config.dst_addr :
>>>> +						     chan->dma_config.src_addr;
>>>> +		len = sg_dma_len(sg);
>>>> +
>>>> +		do {
>>>> +			size_t chunk = min_t(size_t, len, STM32_DMA3_MAX_BLOCK_SIZE);
>>>> +
>>>> +			if (dir == DMA_MEM_TO_DEV) {
>>>> +				src = sg_addr;
>>>> +				dst = dev_addr;
>>>> +
>>>> +				ret = stm32_dma3_chan_prep_hw(chan, dir, &swdesc->ccr, &ctr1, &ctr2,
>>>> +							      src, dst, chunk);
>>>> +
>>>> +				if (FIELD_GET(CTR1_DINC, ctr1))
>>>> +					dev_addr += chunk;
>>>> +			} else { /* (dir == DMA_DEV_TO_MEM || dir == DMA_MEM_TO_MEM) */
>>>> +				src = dev_addr;
>>>> +				dst = sg_addr;
>>>> +
>>>> +				ret = stm32_dma3_chan_prep_hw(chan, dir, &swdesc->ccr, &ctr1, &ctr2,
>>>> +							      src, dst, chunk);
>>>> +
>>>> +				if (FIELD_GET(CTR1_SINC, ctr1))
>>>> +					dev_addr += chunk;
>>>> +			}
>>>> +
>>>> +			if (ret)
>>>> +				goto err_desc_free;
>>>> +
>>>> +			stm32_dma3_chan_prep_hwdesc(chan, swdesc, j, src, dst, chunk,
>>>> +						    ctr1, ctr2, j == (count - 1), false);
>>>> +
>>>> +			sg_addr += chunk;
>>>> +			len -= chunk;
>>>> +			j++;
>>>> +		} while (len);
>>>> +	}
>>>> +
>>>> +	/* Enable Error interrupts */
>>>> +	swdesc->ccr |= CCR_USEIE | CCR_ULEIE | CCR_DTEIE;
>>>> +	/* Enable Transfer state interrupts */
>>>> +	swdesc->ccr |= CCR_TCIE;
>>>> +
>>>> +	swdesc->cyclic = false;
>>>> +
>>>> +	return vchan_tx_prep(&chan->vchan, &swdesc->vdesc, flags);
>>>> +
>>>> +err_desc_free:
>>>> +	stm32_dma3_chan_desc_free(chan, swdesc);
>>>> +
>>>> +	return NULL;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_caps(struct dma_chan *c, struct dma_slave_caps *caps)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +
>>>> +	if (!chan->fifo_size) {
>>>> +		caps->max_burst = 0;
>>>> +		caps->src_addr_widths &= ~BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
>>>> +		caps->dst_addr_widths &= ~BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
>>>> +	} else {
>>>> +		/* Burst transfer should not exceed half of the fifo size */
>>>> +		caps->max_burst = chan->max_burst;
>>>> +		if (caps->max_burst < DMA_SLAVE_BUSWIDTH_8_BYTES) {
>>>> +			caps->src_addr_widths &= ~BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
>>>> +			caps->dst_addr_widths &= ~BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
>>>> +		}
>>>> +	}
>>>> +}
>>>> +
>>>> +static int stm32_dma3_config(struct dma_chan *c, struct dma_slave_config *config)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +
>>>> +	memcpy(&chan->dma_config, config, sizeof(*config));
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static int stm32_dma3_terminate_all(struct dma_chan *c)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +	unsigned long flags;
>>>> +	LIST_HEAD(head);
>>>> +
>>>> +	spin_lock_irqsave(&chan->vchan.lock, flags);
>>>> +
>>>> +	if (chan->swdesc) {
>>>> +		vchan_terminate_vdesc(&chan->swdesc->vdesc);
>>>> +		chan->swdesc = NULL;
>>>> +	}
>>>> +
>>>> +	stm32_dma3_chan_stop(chan);
>>>> +
>>>> +	vchan_get_all_descriptors(&chan->vchan, &head);
>>>> +
>>>> +	spin_unlock_irqrestore(&chan->vchan.lock, flags);
>>>> +	vchan_dma_desc_free_list(&chan->vchan, &head);
>>>> +
>>>> +	dev_dbg(chan2dev(chan), "vchan %pK: terminated\n", &chan->vchan);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_synchronize(struct dma_chan *c)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +
>>>> +	vchan_synchronize(&chan->vchan);
>>>> +}
>>>> +
>>>> +static void stm32_dma3_issue_pending(struct dma_chan *c)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +	unsigned long flags;
>>>> +
>>>> +	spin_lock_irqsave(&chan->vchan.lock, flags);
>>>> +
>>>> +	if (vchan_issue_pending(&chan->vchan) && !chan->swdesc) {
>>>> +		dev_dbg(chan2dev(chan), "vchan %pK: issued\n", &chan->vchan);
>>>> +		stm32_dma3_chan_start(chan);
>>>> +	}
>>>> +
>>>> +	spin_unlock_irqrestore(&chan->vchan.lock, flags);
>>>> +}
>>>> +
>>>> +static bool stm32_dma3_filter_fn(struct dma_chan *c, void *fn_param)
>>>> +{
>>>> +	struct stm32_dma3_chan *chan = to_stm32_dma3_chan(c);
>>>> +	struct stm32_dma3_ddata *ddata = to_stm32_dma3_ddata(chan);
>>>> +	struct stm32_dma3_dt_conf *conf = fn_param;
>>>> +	u32 mask, semcr;
>>>> +	int ret;
>>>> +
>>>> +	dev_dbg(c->device->dev, "%s(%s): req_line=%d ch_conf=%08x tr_conf=%08x\n",
>>>> +		__func__, dma_chan_name(c), conf->req_line, conf->ch_conf, conf->tr_conf);
>>>> +
>>>> +	if (!of_property_read_u32(c->device->dev->of_node, "dma-channel-mask", &mask))
>>>> +		if (!(mask & BIT(chan->id)))
>>>> +			return false;
>>>> +
>>>> +	ret = pm_runtime_resume_and_get(ddata->dma_dev.dev);
>>>> +	if (ret < 0)
>>>> +		return false;
>>>> +	semcr = readl_relaxed(ddata->base + STM32_DMA3_CSEMCR(chan->id));
>>>> +	pm_runtime_put_sync(ddata->dma_dev.dev);
>>>> +
>>>> +	/* Check if chan is free */
>>>> +	if (semcr & CSEMCR_SEM_MUTEX)
>>>> +		return false;
>>>> +
>>>> +	/* Check if chan fifo fits well */
>>>> +	if (FIELD_GET(STM32_DMA3_DT_FIFO, conf->ch_conf) != chan->fifo_size)
>>>> +		return false;
>>>> +
>>>> +	return true;
>>>> +}
>>>> +
>>>> +static struct dma_chan *stm32_dma3_of_xlate(struct of_phandle_args *dma_spec, struct of_dma *ofdma)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = ofdma->of_dma_data;
>>>> +	dma_cap_mask_t mask = ddata->dma_dev.cap_mask;
>>>> +	struct stm32_dma3_dt_conf conf;
>>>> +	struct stm32_dma3_chan *chan;
>>>> +	struct dma_chan *c;
>>>> +
>>>> +	if (dma_spec->args_count < 3) {
>>>> +		dev_err(ddata->dma_dev.dev, "Invalid args count\n");
>>>> +		return NULL;
>>>> +	}
>>>> +
>>>> +	conf.req_line = dma_spec->args[0];
>>>> +	conf.ch_conf = dma_spec->args[1];
>>>> +	conf.tr_conf = dma_spec->args[2];
>>>> +
>>>> +	if (conf.req_line >= ddata->dma_requests) {
>>>> +		dev_err(ddata->dma_dev.dev, "Invalid request line\n");
>>>> +		return NULL;
>>>> +	}
>>>> +
>>>> +	/* Request dma channel among the generic dma controller list */
>>>> +	c = dma_request_channel(mask, stm32_dma3_filter_fn, &conf);
>>>> +	if (!c) {
>>>> +		dev_err(ddata->dma_dev.dev, "No suitable channel found\n");
>>>> +		return NULL;
>>>> +	}
>>>> +
>>>> +	chan = to_stm32_dma3_chan(c);
>>>> +	chan->dt_config = conf;
>>>> +
>>>> +	return c;
>>>> +}
>>>> +
>>>> +static u32 stm32_dma3_check_rif(struct stm32_dma3_ddata *ddata)
>>>> +{
>>>> +	u32 chan_reserved, mask = 0, i, ccidcfgr, invalid_cid = 0;
>>>> +
>>>> +	/* Reserve Secure channels */
>>>> +	chan_reserved = readl_relaxed(ddata->base + STM32_DMA3_SECCFGR);
>>>> +
>>>> +	/*
>>>> +	 * CID filtering must be configured to ensure that the DMA3 channel will inherit the CID of
>>>> +	 * the processor which is configuring and using the given channel.
>>>> +	 * In case CID filtering is not configured, dma-channel-mask property can be used to
>>>> +	 * specify available DMA channels to the kernel.
>>>> +	 */
>>>> +	of_property_read_u32(ddata->dma_dev.dev->of_node, "dma-channel-mask", &mask);
>>>> +
>>>> +	/* Reserve !CID-filtered not in dma-channel-mask, static CID != CID1, CID1 not allowed */
>>>> +	for (i = 0; i < ddata->dma_channels; i++) {
>>>> +		ccidcfgr = readl_relaxed(ddata->base + STM32_DMA3_CCIDCFGR(i));
>>>> +
>>>> +		if (!(ccidcfgr & CCIDCFGR_CFEN)) { /* !CID-filtered */
>>>> +			invalid_cid |= BIT(i);
>>>> +			if (!(mask & BIT(i))) /* Not in dma-channel-mask */
>>>> +				chan_reserved |= BIT(i);
>>>> +		} else { /* CID-filtered */
>>>> +			if (!(ccidcfgr & CCIDCFGR_SEM_EN)) { /* Static CID mode */
>>>> +				if (FIELD_GET(CCIDCFGR_SCID, ccidcfgr) != CCIDCFGR_CID1)
>>>> +					chan_reserved |= BIT(i);
>>>> +			} else { /* Semaphore mode */
>>>> +				if (!FIELD_GET(CCIDCFGR_SEM_WLIST_CID1, ccidcfgr))
>>>> +					chan_reserved |= BIT(i);
>>>> +				ddata->chans[i].semaphore_mode = true;
>>>> +			}
>>>> +		}
>>>> +		dev_dbg(ddata->dma_dev.dev, "chan%d: %s mode, %s\n", i,
>>>> +			!(ccidcfgr & CCIDCFGR_CFEN) ? "!CID-filtered" :
>>>> +			ddata->chans[i].semaphore_mode ? "Semaphore" : "Static CID",
>>>> +			(chan_reserved & BIT(i)) ? "denied" :
>>>> +			mask & BIT(i) ? "force allowed" : "allowed");
>>>> +	}
>>>> +
>>>> +	if (invalid_cid)
>>>> +		dev_warn(ddata->dma_dev.dev, "chan%*pbl have invalid CID configuration\n",
>>>> +			 ddata->dma_channels, &invalid_cid);
>>>> +
>>>> +	return chan_reserved;
>>>> +}
>>>> +
>>>> +static const struct of_device_id stm32_dma3_of_match[] = {
>>>> +	{ .compatible = "st,stm32-dma3", },
>>>> +	{ /* sentinel */},
>>>> +};
>>>> +MODULE_DEVICE_TABLE(of, stm32_dma3_of_match);
>>>> +
>>>> +static int stm32_dma3_probe(struct platform_device *pdev)
>>>> +{
>>>> +	struct device_node *np = pdev->dev.of_node;
>>>> +	struct stm32_dma3_ddata *ddata;
>>>> +	struct reset_control *reset;
>>>> +	struct stm32_dma3_chan *chan;
>>>> +	struct dma_device *dma_dev;
>>>> +	u32 master_ports, chan_reserved, i, verr;
>>>> +	u64 hwcfgr;
>>>> +	int ret;
>>>> +
>>>> +	ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
>>>> +	if (!ddata)
>>>> +		return -ENOMEM;
>>>> +	platform_set_drvdata(pdev, ddata);
>>>> +
>>>> +	dma_dev = &ddata->dma_dev;
>>>> +
>>>> +	ddata->base = devm_platform_ioremap_resource(pdev, 0);
>>>> +	if (IS_ERR(ddata->base))
>>>> +		return PTR_ERR(ddata->base);
>>>> +
>>>> +	ddata->clk = devm_clk_get(&pdev->dev, NULL);
>>>> +	if (IS_ERR(ddata->clk))
>>>> +		return dev_err_probe(&pdev->dev, PTR_ERR(ddata->clk), "Failed to get clk\n");
>>>> +
>>>> +	reset = devm_reset_control_get_optional(&pdev->dev, NULL);
>>>> +	if (IS_ERR(reset))
>>>> +		return dev_err_probe(&pdev->dev, PTR_ERR(reset), "Failed to get reset\n");
>>>> +
>>>> +	ret = clk_prepare_enable(ddata->clk);
>>>> +	if (ret)
>>>> +		return dev_err_probe(&pdev->dev, ret, "Failed to enable clk\n");
>>>> +
>>>> +	reset_control_reset(reset);
>>>> +
>>>> +	INIT_LIST_HEAD(&dma_dev->channels);
>>>> +
>>>> +	dma_cap_set(DMA_SLAVE, dma_dev->cap_mask);
>>>> +	dma_cap_set(DMA_PRIVATE, dma_dev->cap_mask);
>>>> +	dma_dev->dev = &pdev->dev;
>>>> +	/*
>>>> +	 * This controller supports up to 8-byte buswidth depending on the port used and the
>>>> +	 * channel, and can only access address at even boundaries, multiple of the buswidth.
>>>> +	 */
>>>> +	dma_dev->copy_align = DMAENGINE_ALIGN_8_BYTES;
>>>> +	dma_dev->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
>>>> +				   BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
>>>> +				   BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |
>>>> +				   BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
>>>> +	dma_dev->dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |
>>>> +				   BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |
>>>> +				   BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |
>>>> +				   BIT(DMA_SLAVE_BUSWIDTH_8_BYTES);
>>>> +	dma_dev->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV) | BIT(DMA_MEM_TO_MEM);
>>>> +
>>>> +	dma_dev->descriptor_reuse = true;
>>>> +	dma_dev->max_sg_burst = STM32_DMA3_MAX_SEG_SIZE;
>>>> +	dma_dev->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
>>>> +	dma_dev->device_alloc_chan_resources = stm32_dma3_alloc_chan_resources;
>>>> +	dma_dev->device_free_chan_resources = stm32_dma3_free_chan_resources;
>>>> +	dma_dev->device_prep_slave_sg = stm32_dma3_prep_slave_sg;
>>>> +	dma_dev->device_caps = stm32_dma3_caps;
>>>> +	dma_dev->device_config = stm32_dma3_config;
>>>> +	dma_dev->device_terminate_all = stm32_dma3_terminate_all;
>>>> +	dma_dev->device_synchronize = stm32_dma3_synchronize;
>>>> +	dma_dev->device_tx_status = dma_cookie_status;
>>>> +	dma_dev->device_issue_pending = stm32_dma3_issue_pending;
>>>> +
>>>> +	/* if dma_channels is not modified, get it from hwcfgr1 */
>>>> +	if (of_property_read_u32(np, "dma-channels", &ddata->dma_channels)) {
>>>> +		hwcfgr = readl_relaxed(ddata->base + STM32_DMA3_HWCFGR1);
>>>> +		ddata->dma_channels = FIELD_GET(G_NUM_CHANNELS, hwcfgr);
>>>> +	}
>>>> +
>>>> +	/* if dma_requests is not modified, get it from hwcfgr2 */
>>>> +	if (of_property_read_u32(np, "dma-requests", &ddata->dma_requests)) {
>>>> +		hwcfgr = readl_relaxed(ddata->base + STM32_DMA3_HWCFGR2);
>>>> +		ddata->dma_requests = FIELD_GET(G_MAX_REQ_ID, hwcfgr) + 1;
>>>> +	}
>>>> +
>>>> +	/* G_MASTER_PORTS, G_M0_DATA_WIDTH_ENC, G_M1_DATA_WIDTH_ENC in HWCFGR1 */
>>>> +	hwcfgr = readl_relaxed(ddata->base + STM32_DMA3_HWCFGR1);
>>>> +	master_ports = FIELD_GET(G_MASTER_PORTS, hwcfgr);
>>>> +
>>>> +	ddata->ports_max_dw[0] = FIELD_GET(G_M0_DATA_WIDTH_ENC, hwcfgr);
>>>> +	if (master_ports == AXI64 || master_ports == AHB32) /* Single master port */
>>>> +		ddata->ports_max_dw[1] = DW_INVALID;
>>>> +	else /* Dual master ports */
>>>> +		ddata->ports_max_dw[1] = FIELD_GET(G_M1_DATA_WIDTH_ENC, hwcfgr);
>>>> +
>>>> +	ddata->chans = devm_kcalloc(&pdev->dev, ddata->dma_channels, sizeof(*ddata->chans),
>>>> +				    GFP_KERNEL);
>>>> +	if (!ddata->chans) {
>>>> +		ret = -ENOMEM;
>>>> +		goto err_clk_disable;
>>>> +	}
>>>> +
>>>> +	chan_reserved = stm32_dma3_check_rif(ddata);
>>>> +
>>>> +	if (chan_reserved == GENMASK(ddata->dma_channels - 1, 0)) {
>>>> +		ret = -ENODEV;
>>>> +		dev_err_probe(&pdev->dev, ret, "No channel available, abort registration\n");
>>>> +		goto err_clk_disable;
>>>> +	}
>>>> +
>>>> +	/* G_FIFO_SIZE x=0..7 in HWCFGR3 and G_FIFO_SIZE x=8..15 in HWCFGR4 */
>>>> +	hwcfgr = readl_relaxed(ddata->base + STM32_DMA3_HWCFGR3);
>>>> +	hwcfgr |= ((u64)readl_relaxed(ddata->base + STM32_DMA3_HWCFGR4)) << 32;
>>>> +
>>>> +	for (i = 0; i < ddata->dma_channels; i++) {
>>>> +		if (chan_reserved & BIT(i))
>>>> +			continue;
>>>> +
>>>> +		chan = &ddata->chans[i];
>>>> +		chan->id = i;
>>>> +		chan->fifo_size = get_chan_hwcfg(i, G_FIFO_SIZE(i), hwcfgr);
>>>> +		/* If chan->fifo_size > 0 then half of the fifo size, else no burst when no FIFO */
>>>> +		chan->max_burst = (chan->fifo_size) ? (1 << (chan->fifo_size + 1)) / 2 : 0;
>>>> +		chan->vchan.desc_free = stm32_dma3_chan_vdesc_free;
>>>> +
>>>> +		vchan_init(&chan->vchan, dma_dev);
>>>> +	}
>>>> +
>>>> +	ret = dmaenginem_async_device_register(dma_dev);
>>>> +	if (ret)
>>>> +		goto err_clk_disable;
>>>> +
>>>> +	for (i = 0; i < ddata->dma_channels; i++) {
>>>> +		if (chan_reserved & BIT(i))
>>>> +			continue;
>>>> +
>>>> +		ret = platform_get_irq(pdev, i);
>>>> +		if (ret < 0)
>>>> +			goto err_clk_disable;
>>>> +
>>>> +		chan = &ddata->chans[i];
>>>> +		chan->irq = ret;
>>>> +
>>>> +		ret = devm_request_irq(&pdev->dev, chan->irq, stm32_dma3_chan_irq, 0,
>>>> +				       dev_name(chan2dev(chan)), chan);
>>>> +		if (ret) {
>>>> +			dev_err_probe(&pdev->dev, ret, "Failed to request channel %s IRQ\n",
>>>> +				      dev_name(chan2dev(chan)));
>>>> +			goto err_clk_disable;
>>>> +		}
>>>> +	}
>>>> +
>>>> +	ret = of_dma_controller_register(np, stm32_dma3_of_xlate, ddata);
>>>> +	if (ret) {
>>>> +		dev_err_probe(&pdev->dev, ret, "Failed to register controller\n");
>>>> +		goto err_clk_disable;
>>>> +	}
>>>> +
>>>> +	verr = readl_relaxed(ddata->base + STM32_DMA3_VERR);
>>>> +
>>>> +	pm_runtime_set_active(&pdev->dev);
>>>> +	pm_runtime_enable(&pdev->dev);
>>>> +	pm_runtime_get_noresume(&pdev->dev);
>>>> +	pm_runtime_put(&pdev->dev);
>>>> +
>>>> +	dev_info(&pdev->dev, "STM32 DMA3 registered rev:%lu.%lu\n",
>>>> +		 FIELD_GET(VERR_MAJREV, verr), FIELD_GET(VERR_MINREV, verr));
>>>> +
>>>> +	return 0;
>>>> +
>>>> +err_clk_disable:
>>>> +	clk_disable_unprepare(ddata->clk);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static void stm32_dma3_remove(struct platform_device *pdev)
>>>> +{
>>>> +	pm_runtime_disable(&pdev->dev);
>>>> +}
>>>> +
>>>> +static int stm32_dma3_runtime_suspend(struct device *dev)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = dev_get_drvdata(dev);
>>>> +
>>>> +	clk_disable_unprepare(ddata->clk);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static int stm32_dma3_runtime_resume(struct device *dev)
>>>> +{
>>>> +	struct stm32_dma3_ddata *ddata = dev_get_drvdata(dev);
>>>> +	int ret;
>>>> +
>>>> +	ret = clk_prepare_enable(ddata->clk);
>>>> +	if (ret)
>>>> +		dev_err(dev, "Failed to enable clk: %d\n", ret);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static const struct dev_pm_ops stm32_dma3_pm_ops = {
>>>> +	SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, pm_runtime_force_resume)
>>>> +	RUNTIME_PM_OPS(stm32_dma3_runtime_suspend, stm32_dma3_runtime_resume, NULL)
>>>> +};
>>>> +
>>>> +static struct platform_driver stm32_dma3_driver = {
>>>> +	.probe = stm32_dma3_probe,
>>>> +	.remove_new = stm32_dma3_remove,
>>>> +	.driver = {
>>>> +		.name = "stm32-dma3",
>>>> +		.of_match_table = stm32_dma3_of_match,
>>>> +		.pm = pm_ptr(&stm32_dma3_pm_ops),
>>>> +	},
>>>> +};
>>>> +
>>>> +static int __init stm32_dma3_init(void)
>>>> +{
>>>> +	return platform_driver_register(&stm32_dma3_driver);
>>>> +}
>>>> +
>>>> +subsys_initcall(stm32_dma3_init);
>>>> +
>>>> +MODULE_DESCRIPTION("STM32 DMA3 controller driver");
>>>> +MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@foss.st.com>");
>>>> +MODULE_LICENSE("GPL");
>>>> -- 
>>>> 2.25.1
>>>
>>
>> Regards,
>> Amelie