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Subject: Re: [PATCH v2 04/18] phy: cdns-dphy: Add Rx support
To:     Pratyush Yadav <p.yadav@ti.com>,
        Maxime Ripard <mripard@kernel.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        Vinod Koul <vkoul@kernel.org>,
        Peter Ujfalusi <peter.ujfalusi@gmail.com>,
        Steve Longerbeam <slongerbeam@gmail.com>,
        Benoit Parrot <bparrot@ti.com>, linux-media@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-phy@lists.infradead.org, dmaengine@vger.kernel.org
Cc:     Vignesh Raghavendra <vigneshr@ti.com>,
        Chunfeng Yun <chunfeng.yun@mediatek.com>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>
References: <20210526152308.16525-1-p.yadav@ti.com>
 <20210526152308.16525-5-p.yadav@ti.com>
From:   Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Message-ID: <b4de2fb9-6169-136b-e7b3-9eb4b0240eb8@ideasonboard.com>
Date:   Fri, 28 May 2021 09:09:25 +0300
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On 26/05/2021 18:22, Pratyush Yadav wrote:
> The Cadence DPHY can be used to receive image data over the CSI-2
> protocol. Add support for Rx mode. The programming sequence differs from
> the Tx mode so it is added as a separate set of hooks to isolate the two
> paths.
> 
> The PHY is in Tx mode by default and it needs to be set in Rx mode by
> setting the submode to PHY_MIPI_DPHY_SUBMODE_RX in the set_mode()
> callback.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
> ---
> 
> (no changes since v1)
> 
>   drivers/phy/cadence/cdns-dphy.c | 237 ++++++++++++++++++++++++++++++++
>   1 file changed, 237 insertions(+)
> 
> diff --git a/drivers/phy/cadence/cdns-dphy.c b/drivers/phy/cadence/cdns-dphy.c
> index 7d5f7b333893..7bbca679e2bb 100644
> --- a/drivers/phy/cadence/cdns-dphy.c
> +++ b/drivers/phy/cadence/cdns-dphy.c
> @@ -1,11 +1,14 @@
>   // SPDX-License-Identifier: GPL-2.0+
>   /*
>    * Copyright: 2017-2018 Cadence Design Systems, Inc.
> + * Copyright (C) 2021 Texas Instruments Incorporated - https://www.ti.com/
>    */
>   
>   #include <linux/bitops.h>
> +#include <linux/bitfield.h>
>   #include <linux/clk.h>
>   #include <linux/io.h>
> +#include <linux/iopoll.h>
>   #include <linux/module.h>
>   #include <linux/of_address.h>
>   #include <linux/of_device.h>
> @@ -25,10 +28,14 @@
>   #define DPHY_PMA_RCLK(reg)		(0x600 + (reg))
>   #define DPHY_PMA_RDATA(lane, reg)	(0x700 + ((lane) * 0x100) + (reg))
>   #define DPHY_PCS(reg)			(0xb00 + (reg))
> +#define DPHY_ISO(reg)			(0xc00 + (reg))
>   
>   #define DPHY_CMN_SSM			DPHY_PMA_CMN(0x20)
>   #define DPHY_CMN_SSM_EN			BIT(0)
> +#define DPHY_CMN_RX_BANDGAP_TIMER_MASK	GENMASK(8, 1)
>   #define DPHY_CMN_TX_MODE_EN		BIT(9)
> +#define DPHY_CMN_RX_MODE_EN		BIT(10)
> +#define DPHY_CMN_RX_BANDGAP_TIMER	0x14
>   
>   #define DPHY_CMN_PWM			DPHY_PMA_CMN(0x40)
>   #define DPHY_CMN_PWM_DIV(x)		((x) << 20)
> @@ -45,10 +52,27 @@
>   #define DPHY_CMN_OPDIV_FROM_REG		BIT(6)
>   #define DPHY_CMN_OPDIV(x)		((x) << 7)
>   
> +#define DPHY_BAND_CFG			DPHY_PCS(0x0)
> +#define DPHY_BAND_CFG_LEFT_BAND		GENMASK(4, 0)
> +#define DPHY_BAND_CFG_RIGHT_BAND	GENMASK(9, 5)
> +
>   #define DPHY_PSM_CFG			DPHY_PCS(0x4)
>   #define DPHY_PSM_CFG_FROM_REG		BIT(0)
>   #define DPHY_PSM_CLK_DIV(x)		((x) << 1)
>   
> +#define DPHY_POWER_ISLAND_EN_DATA	DPHY_PCS(0x8)
> +#define DPHY_POWER_ISLAND_EN_DATA_VAL	0xaaaaaaaa
> +#define DPHY_POWER_ISLAND_EN_CLK	DPHY_PCS(0xc)
> +#define DPHY_POWER_ISLAND_EN_CLK_VAL	0xaa
> +
> +#define DPHY_ISO_CL_CTRL_L		DPHY_ISO(0x10)
> +#define DPHY_ISO_DL_CTRL_L0		DPHY_ISO(0x14)
> +#define DPHY_ISO_DL_CTRL_L1		DPHY_ISO(0x20)
> +#define DPHY_ISO_DL_CTRL_L2		DPHY_ISO(0x30)
> +#define DPHY_ISO_DL_CTRL_L3		DPHY_ISO(0x3c)
> +#define DPHY_ISO_LANE_READY_BIT		0
> +#define DPHY_ISO_LANE_READY_TIMEOUT_MS	100UL
> +
>   #define DSI_HBP_FRAME_OVERHEAD		12
>   #define DSI_HSA_FRAME_OVERHEAD		14
>   #define DSI_HFP_FRAME_OVERHEAD		6
> @@ -57,6 +81,9 @@
>   #define DSI_NULL_FRAME_OVERHEAD		6
>   #define DSI_EOT_PKT_SIZE		4
>   
> +#define DPHY_LANES_MIN			1
> +#define DPHY_LANES_MAX			4
> +
>   struct cdns_dphy_cfg {
>   	u8 pll_ipdiv;
>   	u8 pll_opdiv;
> @@ -312,6 +339,214 @@ static const struct cdns_dphy_ops tx_ref_dphy_ops = {
>   	.set_psm_div = cdns_dphy_ref_set_psm_div,
>   };
>   
> +static int cdns_dphy_rx_power_on(struct cdns_dphy *dphy)
> +{
> +	/* Start RX state machine. */
> +	writel(DPHY_CMN_SSM_EN | DPHY_CMN_RX_MODE_EN |
> +	       FIELD_PREP(DPHY_CMN_RX_BANDGAP_TIMER_MASK,
> +			  DPHY_CMN_RX_BANDGAP_TIMER),
> +	       dphy->regs + DPHY_CMN_SSM);
> +
> +	return 0;
> +}
> +
> +static int cdns_dphy_rx_power_off(struct cdns_dphy *dphy)
> +{
> +	writel(0, dphy->regs + DPHY_CMN_SSM);
> +
> +	return 0;
> +}
> +
> +static int cdns_dphy_rx_get_band_ctrl(unsigned long hs_clk_rate)
> +{
> +	unsigned int rate = hs_clk_rate / 1000000UL;
> +
> +	if (rate < 80 || rate >= 2500)
> +		return -EOPNOTSUPP;
> +
> +	if (rate >= 80 && rate < 100)
> +		return 0;
> +
> +	if (rate >= 100 && rate < 120)
> +		return 1;
> +
> +	if (rate >= 120 && rate < 160)
> +		return 2;
> +
> +	if (rate >= 160 && rate < 200)
> +		return 3;
> +
> +	if (rate >= 200 && rate < 240)
> +		return 4;
> +
> +	if (rate >= 240 && rate < 280)
> +		return 5;
> +
> +	if (rate >= 280 && rate < 320)
> +		return 6;
> +
> +	if (rate >= 320 && rate < 360)
> +		return 7;
> +
> +	if (rate >= 360 && rate < 400)
> +		return 8;
> +
> +	if (rate >= 400 && rate < 480)
> +		return 9;
> +
> +	if (rate >= 480 && rate < 560)
> +		return 10;
> +
> +	if (rate >= 560 && rate < 640)
> +		return 11;
> +
> +	if (rate >= 640 && rate < 720)
> +		return 12;
> +
> +	if (rate >= 720 && rate < 800)
> +		return 13;
> +
> +	if (rate >= 800 && rate < 880)
> +		return 14;
> +
> +	if (rate >= 880 && rate < 1040)
> +		return 15;
> +
> +	if (rate >= 1040 && rate < 1200)
> +		return 16;
> +
> +	if (rate >= 1200 && rate < 1350)
> +		return 17;
> +
> +	if (rate >= 1350 && rate < 1500)
> +		return 18;
> +
> +	if (rate >= 1500 && rate < 1750)
> +		return 19;
> +
> +	if (rate >= 1750 && rate < 2000)
> +		return 20;
> +
> +	if (rate >= 2000 && rate < 2250)
> +		return 21;
> +
> +	if (rate >= 2250 && rate < 2500)
> +		return 22;
> +

All the above could be handled with a simple table and a for loop.

> +	/* Unreachable. */
> +	WARN(1, "Reached unreachable code.");
> +	return -EINVAL;
> +}
> +
> +static int cdns_dphy_rx_wait_for_bit(void __iomem *addr, unsigned int bit)
> +{
> +	u32 val;
> +
> +	return readl_relaxed_poll_timeout(addr, val, val & BIT(bit), 10,
> +					  DPHY_ISO_LANE_READY_TIMEOUT_MS * 1000);
> +}
> +
> +static int cdns_dphy_rx_wait_lane_ready(struct cdns_dphy *dphy, int lanes)
> +{
> +	void __iomem *reg = dphy->regs;
> +	int ret;
> +
> +	if (lanes < DPHY_LANES_MIN || lanes > DPHY_LANES_MAX)
> +		return -EINVAL;
> +
> +	/* Clock lane */
> +	ret = cdns_dphy_rx_wait_for_bit(reg + DPHY_ISO_CL_CTRL_L,
> +					DPHY_ISO_LANE_READY_BIT);
> +	if (ret)
> +		return ret;
> +
> +	/* Data lanes. Minimum one lane is mandatory. */
> +	ret = cdns_dphy_rx_wait_for_bit(reg + DPHY_ISO_DL_CTRL_L0,
> +					DPHY_ISO_LANE_READY_BIT);
> +	if (ret)
> +		return ret;
> +
> +	if (lanes < 2)
> +		return 0;
> +
> +	ret = cdns_dphy_rx_wait_for_bit(reg + DPHY_ISO_DL_CTRL_L1,
> +					DPHY_ISO_LANE_READY_BIT);
> +	if (ret)
> +		return ret;
> +
> +	if (lanes < 3)
> +		return 0;
> +
> +	ret = cdns_dphy_rx_wait_for_bit(reg + DPHY_ISO_DL_CTRL_L2,
> +					DPHY_ISO_LANE_READY_BIT);
> +	if (ret)
> +		return ret;
> +
> +	if (lanes < 4)
> +		return 0;
> +
> +	ret = cdns_dphy_rx_wait_for_bit(reg + DPHY_ISO_DL_CTRL_L3,
> +					DPHY_ISO_LANE_READY_BIT);
> +	if (ret)
> +		return ret;
> +

This, too, could be handled with an array (for the regs) and a for loop.

  Tomi