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Date:   Wed, 28 Oct 2020 11:20:37 +0100
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     "Ramuthevar,Vadivel MuruganX" 
        <vadivel.muruganx.ramuthevar@linux.intel.com>
Cc:     vigneshr@ti.com, tudor.ambarus@microchip.com,
        linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org,
        robh+dt@kernel.org, boris.brezillon@collabora.com,
        devicetree@vger.kernel.org, simon.k.r.goldschmidt@gmail.com,
        dinguyen@kernel.org, richard@nod.at, cheol.yong.kim@intel.com,
        qi-ming.wu@intel.com
Subject: Re: [RESENDPATCH v15 2/2] mtd: rawnand: Add NAND controller support
 on Intel LGM SoC
Message-ID: <20201028112037.326c06e2@xps13>
In-Reply-To: <20201026073021.33327-3-vadivel.muruganx.ramuthevar@linux.intel.com>
References: <20201026073021.33327-1-vadivel.muruganx.ramuthevar@linux.intel.com>
        <20201026073021.33327-3-vadivel.muruganx.ramuthevar@linux.intel.com>
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Hello,

"Ramuthevar,Vadivel MuruganX"
<vadivel.muruganx.ramuthevar@linux.intel.com> wrote on Mon, 26 Oct 2020
15:30:21 +0800:

> From: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@linux.intel.com>
> 
> This patch adds the new IP of Nand Flash Controller(NFC) support
> on Intel's Lightning Mountain(LGM) SoC.
> 
> DMA is used for burst data transfer operation, also DMA HW supports
> aligned 32bit memory address and aligned data access by default.
> DMA burst of 8 supported. Data register used to support the read/write
> operation from/to device.
> 
> NAND controller driver implements ->exec_op() to replace legacy hooks,
> these specific call-back method to execute NAND operations.

No need to mention legacy hooks here as they are not part of your
driver at all.

> 
> Signed-off-by: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@linux.intel.com>
> ---
>  drivers/mtd/nand/raw/Kconfig                 |   8 +
>  drivers/mtd/nand/raw/Makefile                |   1 +
>  drivers/mtd/nand/raw/intel-nand-controller.c | 734 +++++++++++++++++++++++++++
>  3 files changed, 743 insertions(+)
>  create mode 100644 drivers/mtd/nand/raw/intel-nand-controller.c
> 
> diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
> index 6c46f25b57e2..1b3690fd08dc 100644
> --- a/drivers/mtd/nand/raw/Kconfig
> +++ b/drivers/mtd/nand/raw/Kconfig
> @@ -462,6 +462,14 @@ config MTD_NAND_ARASAN
>  	  Enables the driver for the Arasan NAND flash controller on
>  	  Zynq Ultrascale+ MPSoC.
>  
> +config MTD_NAND_INTEL_LGM
> +	tristate "Support for NAND controller on Intel LGM SoC"
> +	depends on OF || COMPILE_TEST
> +	depends on HAS_IOMEM
> +	help
> +	  Enables support for NAND Flash chips on Intel's LGM SoC.
> +	  NAND flash controller interfaced through the External Bus Unit.
> +
>  comment "Misc"
>  
>  config MTD_SM_COMMON
> diff --git a/drivers/mtd/nand/raw/Makefile b/drivers/mtd/nand/raw/Makefile
> index 2930f5b9015d..9e6037363fc6 100644
> --- a/drivers/mtd/nand/raw/Makefile
> +++ b/drivers/mtd/nand/raw/Makefile
> @@ -58,6 +58,7 @@ obj-$(CONFIG_MTD_NAND_STM32_FMC2)	+= stm32_fmc2_nand.o
>  obj-$(CONFIG_MTD_NAND_MESON)		+= meson_nand.o
>  obj-$(CONFIG_MTD_NAND_CADENCE)		+= cadence-nand-controller.o
>  obj-$(CONFIG_MTD_NAND_ARASAN)		+= arasan-nand-controller.o
> +obj-$(CONFIG_MTD_NAND_INTEL_LGM)	+= intel-nand-controller.o
>  
>  nand-objs := nand_base.o nand_legacy.o nand_bbt.o nand_timings.o nand_ids.o
>  nand-objs += nand_onfi.o
> diff --git a/drivers/mtd/nand/raw/intel-nand-controller.c b/drivers/mtd/nand/raw/intel-nand-controller.c
> new file mode 100644
> index 000000000000..0aefc441c7d5
> --- /dev/null
> +++ b/drivers/mtd/nand/raw/intel-nand-controller.c
> @@ -0,0 +1,734 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/* Copyright (c) 2020 Intel Corporation. */
> +
> +#include <linux/clk.h>
> +#include <linux/completion.h>
> +#include <linux/dmaengine.h>
> +#include <linux/dma-direction.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/iopoll.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +
> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/rawnand.h>
> +#include <linux/mtd/nand_ecc.h>
> +#include <linux/mtd/nand.h>
> +
> +#include <linux/platform_device.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +#include <asm/unaligned.h>
> +
> +#define EBU_CLC			0x000
> +#define EBU_CLC_RST		0x00000000u
> +
> +#define EBU_ADDR_SEL(n)		(0x020 + (n) * 4)
> +/* 5 bits 26:22 included for comparison in the ADDR_SELx */
> +#define EBU_ADDR_MASK(x)	((x) << 4)
> +#define EBU_ADDR_SEL_REGEN	0x1
> +
> +#define EBU_BUSCON(n)		(0x060 + (n) * 4)
> +#define EBU_BUSCON_CMULT_V4	0x1
> +#define EBU_BUSCON_RECOVC(n)	((n) << 2)
> +#define EBU_BUSCON_HOLDC(n)	((n) << 4)
> +#define EBU_BUSCON_WAITRDC(n)	((n) << 6)
> +#define EBU_BUSCON_WAITWRC(n)	((n) << 8)
> +#define EBU_BUSCON_BCGEN_CS	0x0
> +#define EBU_BUSCON_SETUP_EN	BIT(22)
> +#define EBU_BUSCON_ALEC		0xC000
> +
> +#define EBU_CON			0x0B0
> +#define EBU_CON_NANDM_EN	BIT(0)
> +#define EBU_CON_NANDM_DIS	0x0
> +#define EBU_CON_CSMUX_E_EN	BIT(1)
> +#define EBU_CON_ALE_P_LOW	BIT(2)
> +#define EBU_CON_CLE_P_LOW	BIT(3)
> +#define EBU_CON_CS_P_LOW	BIT(4)
> +#define EBU_CON_SE_P_LOW	BIT(5)
> +#define EBU_CON_WP_P_LOW	BIT(6)
> +#define EBU_CON_PRE_P_LOW	BIT(7)
> +#define EBU_CON_IN_CS_S(n)	((n) << 8)
> +#define EBU_CON_OUT_CS_S(n)	((n) << 10)
> +#define EBU_CON_LAT_EN_CS_P	((0x3D) << 18)
> +
> +#define EBU_WAIT		0x0B4
> +#define EBU_WAIT_RDBY		BIT(0)
> +#define EBU_WAIT_WR_C		BIT(3)
> +
> +#define HSNAND_CTL1		0x110
> +#define HSNAND_CTL1_ADDR_SHIFT	24
> +
> +#define HSNAND_CTL2		0x114
> +#define HSNAND_CTL2_ADDR_SHIFT	8
> +#define HSNAND_CTL2_CYC_N_V5	(0x2 << 16)
> +
> +#define HSNAND_INT_MSK_CTL	0x124
> +#define HSNAND_INT_MSK_CTL_WR_C	BIT(4)
> +
> +#define HSNAND_INT_STA		0x128
> +#define HSNAND_INT_STA_WR_C	BIT(4)
> +
> +#define HSNAND_CTL		0x130
> +#define HSNAND_CTL_ENABLE_ECC	BIT(0)
> +#define HSNAND_CTL_GO		BIT(2)
> +#define HSNAND_CTL_CE_SEL_CS(n)	BIT(3 + (n))
> +#define HSNAND_CTL_RW_READ	0x0
> +#define HSNAND_CTL_RW_WRITE	BIT(10)
> +#define HSNAND_CTL_ECC_OFF_V8TH	BIT(11)
> +#define HSNAND_CTL_CKFF_EN	0x0
> +#define HSNAND_CTL_MSG_EN	BIT(17)
> +
> +#define HSNAND_PARA0		0x13c
> +#define HSNAND_PARA0_PAGE_V8192	0x3
> +#define HSNAND_PARA0_PIB_V256	(0x3 << 4)
> +#define HSNAND_PARA0_BYP_EN_NP	0x0
> +#define HSNAND_PARA0_BYP_DEC_NP	0x0
> +#define HSNAND_PARA0_TYPE_ONFI	BIT(18)
> +#define HSNAND_PARA0_ADEP_EN	BIT(21)
> +
> +#define HSNAND_CMSG_0		0x150
> +#define HSNAND_CMSG_1		0x154
> +
> +#define HSNAND_ALE_OFFS		BIT(2)
> +#define HSNAND_CLE_OFFS		BIT(3)
> +#define HSNAND_CS_OFFS		BIT(4)
> +
> +#define HSNAND_ECC_OFFSET	0x008
> +
> +#define NAND_DATA_IFACE_CHECK_ONLY	-1
> +
> +#define MAX_CS	2
> +
> +#define HZ_PER_MHZ	1000000L
> +#define USEC_PER_SEC	1000000L
> +
> +struct ebu_nand_cs {
> +	void __iomem *chipaddr;
> +	dma_addr_t nand_pa;
> +	u32 addr_sel;
> +};
> +
> +struct ebu_nand_controller {
> +	struct nand_controller controller;
> +	struct nand_chip chip;
> +	struct device *dev;
> +	void __iomem *ebu;
> +	void __iomem *hsnand;
> +	struct dma_chan *dma_tx;
> +	struct dma_chan *dma_rx;
> +	struct completion dma_access_complete;
> +	unsigned long clk_rate;
> +	struct clk *clk;
> +	u32 nd_para0;
> +	u8 cs_num;
> +	struct ebu_nand_cs cs[MAX_CS];
> +};
> +
> +static inline struct ebu_nand_controller *nand_to_ebu(struct nand_chip *chip)
> +{
> +	return container_of(chip, struct ebu_nand_controller, chip);
> +}
> +
> +static int ebu_nand_waitrdy(struct nand_chip *chip, unsigned int time_out)

Please mention the unit somewhere.

> +{
> +	struct ebu_nand_controller *ctrl = nand_to_ebu(chip);
> +	u32 status;
> +
> +	return readl_poll_timeout(ctrl->ebu + EBU_WAIT, status,
> +				  (status & EBU_WAIT_RDBY) ||
> +				  (status & EBU_WAIT_WR_C), 20, time_out);
> +}
> +
> +static u8 ebu_nand_readb(struct nand_chip *chip)
> +{
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +	u8 cs_num = ebu_host->cs_num;
> +	u8 val;
> +
> +	val = readb(ebu_host->cs[cs_num].chipaddr + HSNAND_CS_OFFS);
> +	ebu_nand_waitrdy(chip, 1000);
> +	return val;
> +}
> +
> +static void ebu_nand_writeb(struct nand_chip *chip, u32 offset, u8 value)
> +{
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +	u8 cs_num = ebu_host->cs_num;
> +
> +	writeb(value, ebu_host->cs[cs_num].chipaddr + offset);
> +	ebu_nand_waitrdy(chip, 1000);
> +}
> +
> +static void ebu_read_buf(struct nand_chip *chip, u_char *buf, unsigned int len)
> +{
> +	int i;
> +
> +	for (i = 0; i < len; i++)
> +		buf[i] = ebu_nand_readb(chip);
> +}
> +
> +static void ebu_write_buf(struct nand_chip *chip, const u_char *buf, int len)
> +{
> +	int i;
> +
> +	for (i = 0; i < len; i++)
> +		ebu_nand_writeb(chip, HSNAND_CS_OFFS, buf[i]);
> +}
> +
> +static void ebu_nand_disable(struct nand_chip *chip)
> +{
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +
> +	writel(0, ebu_host->ebu + EBU_CON);
> +}
> +
> +static void ebu_select_chip(struct nand_chip *chip)
> +{
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +	void __iomem *nand_con = ebu_host->ebu + EBU_CON;
> +	u32 cs = ebu_host->cs_num;
> +
> +	writel(EBU_CON_NANDM_EN | EBU_CON_CSMUX_E_EN | EBU_CON_CS_P_LOW |
> +	       EBU_CON_SE_P_LOW | EBU_CON_WP_P_LOW | EBU_CON_PRE_P_LOW |
> +	       EBU_CON_IN_CS_S(cs) | EBU_CON_OUT_CS_S(cs) |
> +	       EBU_CON_LAT_EN_CS_P, nand_con);
> +}
> +
> +static void ebu_nand_setup_timing(struct ebu_nand_controller *ctrl,
> +				  const struct nand_sdr_timings *timings)
> +{
> +	unsigned int rate = clk_get_rate(ctrl->clk) / HZ_PER_MHZ;
> +	unsigned int period = DIV_ROUND_UP(USEC_PER_SEC, rate);
> +	u32 trecov, thold, twrwait, trdwait;
> +	u32 reg = 0;
> +
> +	trecov = DIV_ROUND_UP(max(timings->tREA_max, timings->tREH_min),
> +			      period);
> +	reg |= EBU_BUSCON_RECOVC(trecov);
> +
> +	thold = DIV_ROUND_UP(max(timings->tDH_min, timings->tDS_min), period);
> +	reg |= EBU_BUSCON_HOLDC(thold);
> +
> +	trdwait = DIV_ROUND_UP(max(timings->tRC_min, timings->tREH_min),
> +			       period);
> +	reg |= EBU_BUSCON_WAITRDC(trdwait);
> +
> +	twrwait = DIV_ROUND_UP(max(timings->tWC_min, timings->tWH_min), period);
> +	reg |= EBU_BUSCON_WAITWRC(twrwait);
> +
> +	reg |= EBU_BUSCON_CMULT_V4 | EBU_BUSCON_BCGEN_CS | EBU_BUSCON_ALEC |
> +		EBU_BUSCON_SETUP_EN;
> +
> +	writel(reg, ctrl->ebu + EBU_BUSCON(ctrl->cs_num));
> +}
> +
> +static int ebu_nand_set_timings(struct nand_chip *chip, int csline,
> +				const struct nand_interface_config *conf)
> +{
> +	struct ebu_nand_controller *ctrl = nand_to_ebu(chip);
> +	const struct nand_sdr_timings *timings;
> +
> +	timings = nand_get_sdr_timings(conf);
> +	if (IS_ERR(timings))
> +		return PTR_ERR(timings);
> +
> +	if (csline == NAND_DATA_IFACE_CHECK_ONLY)
> +		return 0;
> +
> +	ebu_nand_setup_timing(ctrl, timings);

I don't think adding this helper helps much. You could insert the code
from this function here directly?

> +
> +	return 0;
> +}
> +
> +static int ebu_nand_ooblayout_ecc(struct mtd_info *mtd, int section,
> +				  struct mtd_oob_region *oobregion)
> +{
> +	struct nand_chip *chip = mtd_to_nand(mtd);
> +
> +	if (section)
> +		return -ERANGE;
> +
> +	oobregion->offset = HSNAND_ECC_OFFSET;
> +	oobregion->length = chip->ecc.total;
> +
> +	return 0;
> +}
> +
> +static int ebu_nand_ooblayout_free(struct mtd_info *mtd, int section,
> +				   struct mtd_oob_region *oobregion)
> +{
> +	struct nand_chip *chip = mtd_to_nand(mtd);
> +
> +	if (section)
> +		return -ERANGE;
> +
> +	oobregion->offset = chip->ecc.total + HSNAND_ECC_OFFSET;
> +	oobregion->length = mtd->oobsize - oobregion->offset;
> +
> +	return 0;
> +}
> +
> +static const struct mtd_ooblayout_ops ebu_nand_ooblayout_ops = {
> +	.ecc = ebu_nand_ooblayout_ecc,
> +	.free = ebu_nand_ooblayout_free,
> +};
> +
> +static void ebu_dma_rx_callback(void *cookie)
> +{
> +	struct ebu_nand_controller *ebu_host = cookie;
> +
> +	dmaengine_terminate_async(ebu_host->dma_rx);
> +
> +	complete(&ebu_host->dma_access_complete);
> +}
> +
> +static void ebu_dma_tx_callback(void *cookie)
> +{
> +	struct ebu_nand_controller *ebu_host = cookie;
> +
> +	dmaengine_terminate_async(ebu_host->dma_tx);
> +
> +	complete(&ebu_host->dma_access_complete);

Please check return codes when they are relevant, and return the
errors. Also treat them below.

> +}
> +
> +static int ebu_dma_start(struct ebu_nand_controller *ebu_host, u32 dir,
> +			 const u8 *buf, u32 len)
> +{
> +	struct dma_async_tx_descriptor *tx;
> +	struct completion *dma_completion;
> +	dma_async_tx_callback callback;
> +	struct dma_chan *chan;
> +	dma_cookie_t cookie;
> +	unsigned long flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
> +	dma_addr_t buf_dma;
> +	int ret;
> +	u32 timeout;
> +
> +	if (dir == DMA_DEV_TO_MEM) {
> +		chan = ebu_host->dma_rx;
> +		dma_completion = &ebu_host->dma_access_complete;
> +		callback = ebu_dma_rx_callback;
> +	} else {
> +		chan = ebu_host->dma_tx;
> +		dma_completion = &ebu_host->dma_access_complete;
> +		callback = ebu_dma_tx_callback;
> +	}
> +
> +	buf_dma = dma_map_single(chan->device->dev, (void *)buf, len, dir);
> +	if (dma_mapping_error(chan->device->dev, buf_dma)) {
> +		dev_err(ebu_host->dev, "Failed to map DMA buffer\n");
> +		ret = -EIO;
> +		goto err_unmap;
> +	}
> +
> +	tx = dmaengine_prep_slave_single(chan, buf_dma, len, dir, flags);
> +	if (!tx)
> +		return -ENXIO;
> +
> +	tx->callback = callback;
> +	tx->callback_param = ebu_host;
> +	cookie = tx->tx_submit(tx);
> +
> +	ret = dma_submit_error(cookie);
> +	if (ret) {
> +		dev_err(ebu_host->dev, "dma_submit_error %d\n", cookie);
> +		ret = -EIO;
> +		goto err_unmap;
> +	}
> +
> +	init_completion(dma_completion);
> +	dma_async_issue_pending(chan);
> +
> +	/* Wait DMA to finish the data transfer.*/
> +	timeout = wait_for_completion_timeout(dma_completion, msecs_to_jiffies(1000));
> +	if (!timeout) {
> +		dev_err(ebu_host->dev, "I/O Error in DMA RX (status %d)\n",
> +			dmaengine_tx_status(chan, cookie, NULL));
> +		dmaengine_terminate_sync(chan);
> +		ret = -ETIMEDOUT;
> +		goto err_unmap;
> +	}
> +
> +	return 0;
> +
> +err_unmap:
> +	dma_unmap_single(ebu_host->dev, buf_dma, len, dir);
> +
> +	return ret;
> +}
> +
> +static void ebu_nand_trigger(struct ebu_nand_controller *ebu_host,
> +			     int page, u32 cmd)
> +{
> +	unsigned int val;
> +
> +	val = cmd | (page & 0xFF) << HSNAND_CTL1_ADDR_SHIFT;
> +	writel(val, ebu_host->hsnand + HSNAND_CTL1);
> +	val = (page & 0xFFFF00) >> 8 | HSNAND_CTL2_CYC_N_V5;
> +	writel(val, ebu_host->hsnand + HSNAND_CTL2);
> +
> +	writel(ebu_host->nd_para0, ebu_host->hsnand + HSNAND_PARA0);
> +
> +	/* clear first, will update later */
> +	writel(0xFFFFFFFF, ebu_host->hsnand + HSNAND_CMSG_0);
> +	writel(0xFFFFFFFF, ebu_host->hsnand + HSNAND_CMSG_1);
> +
> +	writel(HSNAND_INT_MSK_CTL_WR_C,
> +	       ebu_host->hsnand + HSNAND_INT_MSK_CTL);
> +
> +	if (!cmd)
> +		val = HSNAND_CTL_RW_READ;
> +	else
> +		val = HSNAND_CTL_RW_WRITE;
> +
> +	writel(HSNAND_CTL_MSG_EN | HSNAND_CTL_CKFF_EN |
> +	       HSNAND_CTL_ECC_OFF_V8TH | HSNAND_CTL_CE_SEL_CS(ebu_host->cs_num) |
> +	       HSNAND_CTL_ENABLE_ECC | HSNAND_CTL_GO | val,
> +	       ebu_host->hsnand + HSNAND_CTL);
> +}
> +
> +static int ebu_nand_read_page_hwecc(struct nand_chip *chip, u8 *buf,
> +				    int oob_required, int page)
> +{
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +	int ret, reg_data;
> +
> +	ebu_nand_trigger(ebu_host, page, NAND_CMD_READ0);
> +
> +	ret = ebu_dma_start(ebu_host, DMA_DEV_TO_MEM, buf, mtd->writesize);
> +	if (ret)
> +		return ret;
> +
> +	if (oob_required)
> +		chip->ecc.read_oob(chip, page);
> +
> +	reg_data = readl(ebu_host->hsnand + HSNAND_CTL);
> +	reg_data &= ~HSNAND_CTL_GO;
> +	writel(reg_data, ebu_host->hsnand + HSNAND_CTL);
> +
> +	return 0;
> +}
> +
> +static int ebu_nand_write_page_hwecc(struct nand_chip *chip, const u8 *buf,
> +				     int oob_required, int page)
> +{
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +	void __iomem *int_sta = ebu_host->hsnand + HSNAND_INT_STA;
> +	int reg_data, ret, val;
> +	u32 reg;
> +
> +	ebu_nand_trigger(ebu_host, page, NAND_CMD_SEQIN);
> +
> +	ret = ebu_dma_start(ebu_host, DMA_MEM_TO_DEV, buf, mtd->writesize);
> +	if (ret)
> +		return ret;
> +
> +	if (oob_required) {
> +		reg = get_unaligned_le32(chip->oob_poi);
> +		writel(reg, ebu_host->hsnand + HSNAND_CMSG_0);
> +
> +		reg = get_unaligned_le32(chip->oob_poi + 4);
> +		writel(reg, ebu_host->hsnand + HSNAND_CMSG_1);
> +	}
> +
> +	ret = readl_poll_timeout_atomic(int_sta, val, !(val & HSNAND_INT_STA_WR_C),
> +					10, 1000);
> +	if (ret)
> +		return ret;
> +
> +	reg_data = readl(ebu_host->hsnand + HSNAND_CTL);
> +	reg_data &= ~HSNAND_CTL_GO;
> +	writel(reg_data, ebu_host->hsnand + HSNAND_CTL);
> +
> +	return 0;
> +}
> +
> +static const u8 ecc_strength[] = { 1, 1, 4, 8, 24, 32, 40, 60, };
> +
> +static int ebu_nand_attach_chip(struct nand_chip *chip)
> +{
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +	u32 ecc_steps, ecc_bytes, ecc_total, pagesize, pg_per_blk;
> +	u32 ecc_strength_ds = chip->ecc.strength;
> +	u32 ecc_size = chip->ecc.size;
> +	u32 writesize = mtd->writesize;
> +	u32 blocksize = mtd->erasesize;
> +	int bch_algo, start, val;
> +
> +	/* Default to an ECC size of 512 */
> +	if (!chip->ecc.size)
> +		chip->ecc.size = 512;
> +
> +	switch (ecc_size) {
> +	case 512:
> +		start = 1;
> +		if (!ecc_strength_ds)
> +			ecc_strength_ds = 4;
> +		break;
> +	case 1024:
> +		start = 4;
> +		if (!ecc_strength_ds)
> +			ecc_strength_ds = 32;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	/* BCH ECC algorithm Settings for number of bits per 512B/1024B */
> +	bch_algo = round_up(start + 1, 4);
> +	for (val = start; val < bch_algo; val++) {
> +		if (ecc_strength_ds == ecc_strength[val])
> +			break;
> +	}
> +	if (val == bch_algo)
> +		return -EINVAL;
> +
> +	if (ecc_strength_ds == 8)
> +		ecc_bytes = 14;
> +	else
> +		ecc_bytes = DIV_ROUND_UP(ecc_strength_ds * fls(8 * ecc_size), 8);
> +
> +	ecc_steps = writesize / ecc_size;
> +	ecc_total = ecc_steps * ecc_bytes;
> +	if ((ecc_total + 8) > mtd->oobsize)
> +		return -ERANGE;
> +
> +	chip->ecc.total = ecc_total;
> +	pagesize = fls(writesize >> 11);
> +	if (pagesize > HSNAND_PARA0_PAGE_V8192)
> +		return -ERANGE;
> +
> +	pg_per_blk = fls((blocksize / writesize) >> 6) / 8;
> +	if (pg_per_blk > HSNAND_PARA0_PIB_V256)
> +		return -ERANGE;
> +
> +	ebu_host->nd_para0 = pagesize | pg_per_blk | HSNAND_PARA0_BYP_EN_NP |
> +			     HSNAND_PARA0_BYP_DEC_NP | HSNAND_PARA0_ADEP_EN |
> +			     HSNAND_PARA0_TYPE_ONFI | (val << 29);
> +
> +	mtd_set_ooblayout(mtd, &ebu_nand_ooblayout_ops);
> +	chip->ecc.read_page = ebu_nand_read_page_hwecc;
> +	chip->ecc.write_page = ebu_nand_write_page_hwecc;
> +
> +	return 0;
> +}
> +
> +static int ebu_nand_exec_op(struct nand_chip *chip,
> +			    const struct nand_operation *op, bool check_only)
> +{
> +	const struct nand_op_instr *instr = NULL;
> +	unsigned int op_id;
> +	int i, time_out, ret = 0;
> +
> +	if (check_only)
> +		return 0;
> +
> +	ebu_select_chip(chip);
> +	for (op_id = 0; op_id < op->ninstrs; op_id++) {
> +		instr = &op->instrs[op_id];
> +
> +		switch (instr->type) {
> +		case NAND_OP_CMD_INSTR:
> +			ebu_nand_writeb(chip, HSNAND_CLE_OFFS | HSNAND_CS_OFFS,
> +					instr->ctx.cmd.opcode);
> +			break;
> +
> +		case NAND_OP_ADDR_INSTR:
> +			for (i = 0; i < instr->ctx.addr.naddrs; i++)
> +				ebu_nand_writeb(chip,
> +						HSNAND_ALE_OFFS | HSNAND_CS_OFFS,
> +						instr->ctx.addr.addrs[i]);
> +			break;
> +
> +		case NAND_OP_DATA_IN_INSTR:
> +			ebu_read_buf(chip, instr->ctx.data.buf.in,
> +				     instr->ctx.data.len);
> +			break;
> +
> +		case NAND_OP_DATA_OUT_INSTR:
> +			ebu_write_buf(chip, instr->ctx.data.buf.out,
> +				      instr->ctx.data.len);
> +			break;
> +
> +		case NAND_OP_WAITRDY_INSTR:
> +			time_out = instr->ctx.waitrdy.timeout_ms * 1000;
> +			ret = ebu_nand_waitrdy(chip, time_out);
> +			break;
> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +static const struct nand_controller_ops ebu_nand_controller_ops = {
> +	.attach_chip = ebu_nand_attach_chip,
> +	.setup_interface = ebu_nand_set_timings,
> +	.exec_op = ebu_nand_exec_op,
> +};
> +
> +static void ebu_dma_cleanup(struct ebu_nand_controller *ebu_host)
> +{
> +	if (ebu_host->dma_rx)
> +		dma_release_channel(ebu_host->dma_rx);
> +
> +	if (ebu_host->dma_tx)
> +		dma_release_channel(ebu_host->dma_tx);
> +}
> +
> +static int ebu_nand_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct ebu_nand_controller *ebu_host;
> +	struct nand_chip *nand;
> +	struct mtd_info *mtd;
> +	struct resource *res;
> +	char *resname;
> +	int ret, i;
> +	u32 reg;
> +
> +	ebu_host = devm_kzalloc(dev, sizeof(*ebu_host), GFP_KERNEL);
> +	if (!ebu_host)
> +		return -ENOMEM;
> +
> +	ebu_host->dev = dev;
> +	nand_controller_init(&ebu_host->controller);
> +
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "ebunand");
> +	ebu_host->ebu = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(ebu_host->ebu))
> +		return PTR_ERR(ebu_host->ebu);
> +
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "hsnand");
> +	ebu_host->hsnand = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(ebu_host->hsnand))
> +		return PTR_ERR(ebu_host->hsnand);
> +
> +	ret = device_property_read_u32(dev, "nand,cs", &reg);

There is no nand,cs property. Use 'reg' instead.

> +	if (ret) {
> +		dev_err(dev, "failed to get chip select: %d\n", ret);
> +		return ret;
> +	}
> +	ebu_host->cs_num = reg;

The following for loop is weird, above you can only store a single cs
number, while below you seem to reserve serveral memory areas. Please
clarify this code.

> +
> +	for (i = 0; i < MAX_CS; i++) {
> +		resname = devm_kasprintf(dev, GFP_KERNEL, "nand_cs%d", i);
> +		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> +						   resname);
> +		ebu_host->cs[i].chipaddr = devm_ioremap_resource(dev, res);
> +		ebu_host->cs[i].nand_pa = res->start;
> +		if (IS_ERR(ebu_host->cs[i].chipaddr))
> +			return PTR_ERR(ebu_host->cs[i].chipaddr);
> +	}
> +
> +	ebu_host->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(ebu_host->clk))
> +		return dev_err_probe(dev, PTR_ERR(ebu_host->clk),
> +				     "failed to get clock\n");
> +
> +	ret = clk_prepare_enable(ebu_host->clk);
> +	if (ret) {
> +		dev_err(dev, "failed to enable clock: %d\n", ret);
> +		return ret;
> +	}
> +	ebu_host->clk_rate = clk_get_rate(ebu_host->clk);
> +
> +	ebu_host->dma_tx = dma_request_chan(dev, "tx");
> +	if (IS_ERR(ebu_host->dma_tx))
> +		return dev_err_probe(dev, PTR_ERR(ebu_host->dma_tx),
> +				     "failed to request DMA tx chan!.\n");
> +
> +	ebu_host->dma_rx = dma_request_chan(dev, "rx");
> +	if (IS_ERR(ebu_host->dma_rx))
> +		return dev_err_probe(dev, PTR_ERR(ebu_host->dma_rx),
> +				     "failed to request DMA rx chan!.\n");
> +
> +	for (i = 0; i < MAX_CS; i++) {
> +		resname = devm_kasprintf(dev, GFP_KERNEL, "addr_sel%d", i);
> +		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> +						   resname);
> +		if (!res)
> +			return -EINVAL;
> +		ebu_host->cs[i].addr_sel = res->start;
> +		writel(ebu_host->cs[i].addr_sel | EBU_ADDR_MASK(5) |
> +		       EBU_ADDR_SEL_REGEN, ebu_host->ebu + EBU_ADDR_SEL(i));
> +	}
> +
> +	nand_set_flash_node(&ebu_host->chip, dev->of_node);
> +	if (!mtd->name) {
> +		dev_err(ebu_host->dev, "NAND label property is mandatory\n");
> +		return -EINVAL;
> +	}
> +
> +	mtd = nand_to_mtd(&ebu_host->chip);
> +	mtd->dev.parent = dev;
> +	ebu_host->dev = dev;
> +
> +	platform_set_drvdata(pdev, ebu_host);
> +	nand_set_controller_data(&ebu_host->chip, ebu_host);
> +
> +	nand = &ebu_host->chip;
> +	nand->controller = &ebu_host->controller;
> +	nand->controller->ops = &ebu_nand_controller_ops;
> +
> +	/* Scan to find existence of the device */
> +	ret = nand_scan(&ebu_host->chip, 1);
> +	if (ret)
> +		goto err_cleanup_dma;
> +
> +	ret = mtd_device_register(mtd, NULL, 0);
> +	if (ret)
> +		goto err_clean_nand;
> +
> +	return 0;
> +
> +err_clean_nand:
> +	nand_cleanup(&ebu_host->chip);
> +err_cleanup_dma:
> +	ebu_dma_cleanup(ebu_host);
> +	clk_disable_unprepare(ebu_host->clk);
> +
> +	return ret;
> +}
> +
> +static int ebu_nand_remove(struct platform_device *pdev)
> +{
> +	struct ebu_nand_controller *ebu_host = platform_get_drvdata(pdev);
> +	int ret;
> +
> +	ret = mtd_device_unregister(nand_to_mtd(&ebu_host->chip));
> +	WARN_ON(ret);
> +	nand_cleanup(&ebu_host->chip);
> +	ebu_nand_disable(&ebu_host->chip);
> +	ebu_dma_cleanup(ebu_host);
> +	clk_disable_unprepare(ebu_host->clk);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id ebu_nand_match[] = {
> +	{ .compatible = "intel,nand-controller", },

No version or soc in the compatible? (not mandatory).

> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, ebu_nand_match);
> +
> +static struct platform_driver ebu_nand_driver = {
> +	.probe = ebu_nand_probe,
> +	.remove = ebu_nand_remove,
> +	.driver = {
> +		.name = "intel-nand-controller",
> +		.of_match_table = ebu_nand_match,
> +	},
> +
> +};
> +module_platform_driver(ebu_nand_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Vadivel Murugan R <vadivel.muruganx.ramuthevar@intel.com>");
> +MODULE_DESCRIPTION("Intel's LGM External Bus NAND Controller driver");

Thanks,
Miquèl