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Date:   Thu, 23 May 2019 10:54:17 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Torsten Duwe <duwe@lst.de>
Cc:     Maxime Ripard <maxime.ripard@bootlin.com>,
        Chen-Yu Tsai <wens@csie.org>, Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Andrzej Hajda <a.hajda@samsung.com>,
        Icenowy Zheng <icenowy@aosc.io>,
        Sean Paul <seanpaul@chromium.org>,
        Vasily Khoruzhick <anarsoul@gmail.com>,
        Harald Geyer <harald@ccbib.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/6] drm/bridge: extract some Analogix I2C DP common code
Message-ID: <20190523075417.GB5971@pendragon.ideasonboard.com>
References: <20190523065013.2719D68B05@newverein.lst.de>
 <20190523065352.8FD7668B05@newverein.lst.de>
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Hi Torsten,

Thank you for the patch.

On Thu, May 23, 2019 at 08:53:52AM +0200, Torsten Duwe wrote:
> From: Icenowy Zheng <icenowy@aosc.io>
> 
> Some code can be shared within different DP bridges by Analogix.
> 
> Extract them to a new module.
> 
> Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
> Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
> Signed-off-by: Torsten Duwe <duwe@suse.de>
> ---
>  drivers/gpu/drm/bridge/analogix/Kconfig            |   4 +
>  drivers/gpu/drm/bridge/analogix/Makefile           |   2 +
>  drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c | 146 +-----------------
>  .../gpu/drm/bridge/analogix/analogix-i2c-dptx.c    | 169 +++++++++++++++++++++
>  .../gpu/drm/bridge/analogix/analogix-i2c-dptx.h    |   2 +
>  5 files changed, 178 insertions(+), 145 deletions(-)
>  create mode 100644 drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.c
> 
> diff --git a/drivers/gpu/drm/bridge/analogix/Kconfig b/drivers/gpu/drm/bridge/analogix/Kconfig
> index c4d343a2f04d..ed2d05c12546 100644
> --- a/drivers/gpu/drm/bridge/analogix/Kconfig
> +++ b/drivers/gpu/drm/bridge/analogix/Kconfig
> @@ -1,6 +1,7 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  config DRM_ANALOGIX_ANX78XX
>  	tristate "Analogix ANX78XX bridge"
> +	select DRM_ANALOGIX_DP_I2C
>  	select DRM_KMS_HELPER
>  	select REGMAP_I2C
>  	help
> @@ -11,3 +12,6 @@ config DRM_ANALOGIX_ANX78XX
>  config DRM_ANALOGIX_DP
>  	tristate
>  	depends on DRM
> +
> +config DRM_ANALOGIX_DP_I2C
> +	tristate
> diff --git a/drivers/gpu/drm/bridge/analogix/Makefile b/drivers/gpu/drm/bridge/analogix/Makefile
> index ce1687e60975..2d523b67487d 100644
> --- a/drivers/gpu/drm/bridge/analogix/Makefile
> +++ b/drivers/gpu/drm/bridge/analogix/Makefile
> @@ -1,4 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  analogix_dp-objs := analogix_dp_core.o analogix_dp_reg.o
> +analogix_dp_i2c-objs := analogix-i2c-dptx.o
>  obj-$(CONFIG_DRM_ANALOGIX_ANX78XX) += analogix-anx78xx.o
>  obj-$(CONFIG_DRM_ANALOGIX_DP) += analogix_dp.o
> +obj-$(CONFIG_DRM_ANALOGIX_DP_I2C) += analogix_dp_i2c.o

Do we need a separate module for this, or could it be included in
analogix_dp ?

> diff --git a/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c b/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c
> index f8433c93f463..bf8291d0ddd0 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c
> +++ b/drivers/gpu/drm/bridge/analogix/analogix-anx78xx.c
> @@ -45,8 +45,6 @@
>  #define I2C_IDX_RX_P1		4
>  
>  #define XTAL_CLK		270 /* 27M */
> -#define AUX_CH_BUFFER_SIZE	16
> -#define AUX_WAIT_TIMEOUT_MS	15
>  
>  static const u8 anx78xx_i2c_addresses[] = {
>  	[I2C_IDX_TX_P0] = TX_P0,
> @@ -109,153 +107,11 @@ static int anx78xx_clear_bits(struct regmap *map, u8 reg, u8 mask)
>  	return regmap_update_bits(map, reg, mask, 0);
>  }
>  
> -static bool anx78xx_aux_op_finished(struct anx78xx *anx78xx)
> -{
> -	unsigned int value;
> -	int err;
> -
> -	err = regmap_read(anx78xx->map[I2C_IDX_TX_P0], SP_DP_AUX_CH_CTRL2_REG,
> -			  &value);
> -	if (err < 0)
> -		return false;
> -
> -	return (value & SP_AUX_EN) == 0;
> -}
> -
> -static int anx78xx_aux_wait(struct anx78xx *anx78xx)
> -{
> -	unsigned long timeout;
> -	unsigned int status;
> -	int err;
> -
> -	timeout = jiffies + msecs_to_jiffies(AUX_WAIT_TIMEOUT_MS) + 1;
> -
> -	while (!anx78xx_aux_op_finished(anx78xx)) {
> -		if (time_after(jiffies, timeout)) {
> -			if (!anx78xx_aux_op_finished(anx78xx)) {
> -				DRM_ERROR("Timed out waiting AUX to finish\n");
> -				return -ETIMEDOUT;
> -			}
> -
> -			break;
> -		}
> -
> -		usleep_range(1000, 2000);
> -	}
> -
> -	/* Read the AUX channel access status */
> -	err = regmap_read(anx78xx->map[I2C_IDX_TX_P0], SP_AUX_CH_STATUS_REG,
> -			  &status);
> -	if (err < 0) {
> -		DRM_ERROR("Failed to read from AUX channel: %d\n", err);
> -		return err;
> -	}
> -
> -	if (status & SP_AUX_STATUS) {
> -		DRM_ERROR("Failed to wait for AUX channel (status: %02x)\n",
> -			  status);
> -		return -ETIMEDOUT;
> -	}
> -
> -	return 0;
> -}
> -
> -static int anx78xx_aux_address(struct anx78xx *anx78xx, unsigned int addr)
> -{
> -	int err;
> -
> -	err = regmap_write(anx78xx->map[I2C_IDX_TX_P0], SP_AUX_ADDR_7_0_REG,
> -			   addr & 0xff);
> -	if (err)
> -		return err;
> -
> -	err = regmap_write(anx78xx->map[I2C_IDX_TX_P0], SP_AUX_ADDR_15_8_REG,
> -			   (addr & 0xff00) >> 8);
> -	if (err)
> -		return err;
> -
> -	/*
> -	 * DP AUX CH Address Register #2, only update bits[3:0]
> -	 * [7:4] RESERVED
> -	 * [3:0] AUX_ADDR[19:16], Register control AUX CH address.
> -	 */
> -	err = regmap_update_bits(anx78xx->map[I2C_IDX_TX_P0],
> -				 SP_AUX_ADDR_19_16_REG,
> -				 SP_AUX_ADDR_19_16_MASK,
> -				 (addr & 0xf0000) >> 16);
> -
> -	if (err)
> -		return err;
> -
> -	return 0;
> -}
> -
>  static ssize_t anx78xx_aux_transfer(struct drm_dp_aux *aux,
>  				    struct drm_dp_aux_msg *msg)
>  {
>  	struct anx78xx *anx78xx = container_of(aux, struct anx78xx, aux);
> -	u8 ctrl1 = msg->request;
> -	u8 ctrl2 = SP_AUX_EN;
> -	u8 *buffer = msg->buffer;
> -	int err;
> -
> -	/* The DP AUX transmit and receive buffer has 16 bytes. */
> -	if (WARN_ON(msg->size > AUX_CH_BUFFER_SIZE))
> -		return -E2BIG;
> -
> -	/* Zero-sized messages specify address-only transactions. */
> -	if (msg->size < 1)
> -		ctrl2 |= SP_ADDR_ONLY;
> -	else	/* For non-zero-sized set the length field. */
> -		ctrl1 |= (msg->size - 1) << SP_AUX_LENGTH_SHIFT;
> -
> -	if ((msg->request & DP_AUX_I2C_READ) == 0) {
> -		/* When WRITE | MOT write values to data buffer */
> -		err = regmap_bulk_write(anx78xx->map[I2C_IDX_TX_P0],
> -					SP_DP_BUF_DATA0_REG, buffer,
> -					msg->size);
> -		if (err)
> -			return err;
> -	}
> -
> -	/* Write address and request */
> -	err = anx78xx_aux_address(anx78xx, msg->address);
> -	if (err)
> -		return err;
> -
> -	err = regmap_write(anx78xx->map[I2C_IDX_TX_P0], SP_DP_AUX_CH_CTRL1_REG,
> -			   ctrl1);
> -	if (err)
> -		return err;
> -
> -	/* Start transaction */
> -	err = regmap_update_bits(anx78xx->map[I2C_IDX_TX_P0],
> -				 SP_DP_AUX_CH_CTRL2_REG, SP_ADDR_ONLY |
> -				 SP_AUX_EN, ctrl2);
> -	if (err)
> -		return err;
> -
> -	err = anx78xx_aux_wait(anx78xx);
> -	if (err)
> -		return err;
> -
> -	msg->reply = DP_AUX_I2C_REPLY_ACK;
> -
> -	if ((msg->size > 0) && (msg->request & DP_AUX_I2C_READ)) {
> -		/* Read values from data buffer */
> -		err = regmap_bulk_read(anx78xx->map[I2C_IDX_TX_P0],
> -				       SP_DP_BUF_DATA0_REG, buffer,
> -				       msg->size);
> -		if (err)
> -			return err;
> -	}
> -
> -	err = anx78xx_clear_bits(anx78xx->map[I2C_IDX_TX_P0],
> -				 SP_DP_AUX_CH_CTRL2_REG, SP_ADDR_ONLY);
> -	if (err)
> -		return err;
> -
> -	return msg->size;
> +	return anx_aux_transfer(anx78xx->map[I2C_IDX_TX_P0], msg);
>  }
>  
>  static int anx78xx_set_hpd(struct anx78xx *anx78xx)
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.c b/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.c
> new file mode 100644
> index 000000000000..9cb30962032e
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.c
> @@ -0,0 +1,169 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright(c) 2017 Icenowy Zheng <icenowy@aosc.io>
> + *
> + * Based on analogix-anx78xx.c, which is:
> + *   Copyright(c) 2016, Analogix Semiconductor. All rights reserved.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +
> +#include <drm/drm.h>
> +#include <drm/drmP.h>
> +#include <drm/drm_dp_helper.h>
> +
> +#include "analogix-i2c-dptx.h"
> +
> +#define AUX_WAIT_TIMEOUT_MS	15
> +#define AUX_CH_BUFFER_SIZE	16
> +
> +static int anx_clear_bits(struct regmap *map, u8 reg, u8 mask)
> +{
> +	return regmap_update_bits(map, reg, mask, 0);
> +}
> +
> +static bool anx_aux_op_finished(struct regmap *map_dptx)
> +{
> +	unsigned int value;
> +	int err;
> +
> +	err = regmap_read(map_dptx, SP_DP_AUX_CH_CTRL2_REG, &value);
> +	if (err < 0)
> +		return false;
> +
> +	return (value & SP_AUX_EN) == 0;
> +}
> +
> +static int anx_aux_wait(struct regmap *map_dptx)
> +{
> +	unsigned long timeout;
> +	unsigned int status;
> +	int err;
> +
> +	timeout = jiffies + msecs_to_jiffies(AUX_WAIT_TIMEOUT_MS) + 1;
> +
> +	while (!anx_aux_op_finished(map_dptx)) {
> +		if (time_after(jiffies, timeout)) {
> +			if (!anx_aux_op_finished(map_dptx)) {
> +				DRM_ERROR("Timed out waiting AUX to finish\n");
> +				return -ETIMEDOUT;
> +			}
> +
> +			break;
> +		}
> +
> +		usleep_range(1000, 2000);
> +	}
> +
> +	/* Read the AUX channel access status */
> +	err = regmap_read(map_dptx, SP_AUX_CH_STATUS_REG, &status);
> +	if (err < 0) {
> +		DRM_ERROR("Failed to read from AUX channel: %d\n", err);
> +		return err;
> +	}
> +
> +	if (status & SP_AUX_STATUS) {
> +		DRM_ERROR("Failed to wait for AUX channel (status: %02x)\n",
> +			  status);
> +		return -ETIMEDOUT;
> +	}
> +
> +	return 0;
> +}
> +
> +static int anx_aux_address(struct regmap *map_dptx, unsigned int addr)
> +{
> +	int err;
> +
> +	err = regmap_write(map_dptx, SP_AUX_ADDR_7_0_REG, addr & 0xff);
> +	if (err)
> +		return err;
> +
> +	err = regmap_write(map_dptx, SP_AUX_ADDR_15_8_REG,
> +			   (addr & 0xff00) >> 8);
> +	if (err)
> +		return err;
> +
> +	/*
> +	 * DP AUX CH Address Register #2, only update bits[3:0]
> +	 * [7:4] RESERVED
> +	 * [3:0] AUX_ADDR[19:16], Register control AUX CH address.
> +	 */
> +	err = regmap_update_bits(map_dptx, SP_AUX_ADDR_19_16_REG,
> +				 SP_AUX_ADDR_19_16_MASK,
> +				 (addr & 0xf0000) >> 16);
> +
> +	if (err)
> +		return err;
> +
> +	return 0;
> +}
> +
> +ssize_t anx_aux_transfer(struct regmap *map_dptx, struct drm_dp_aux_msg *msg)
> +{
> +	u8 ctrl1 = msg->request;
> +	u8 ctrl2 = SP_AUX_EN;
> +	u8 *buffer = msg->buffer;
> +	int err;
> +
> +	/* The DP AUX transmit and receive buffer has 16 bytes. */
> +	if (WARN_ON(msg->size > AUX_CH_BUFFER_SIZE))
> +		return -E2BIG;
> +
> +	/* Zero-sized messages specify address-only transactions. */
> +	if (msg->size < 1)
> +		ctrl2 |= SP_ADDR_ONLY;
> +	else	/* For non-zero-sized set the length field. */
> +		ctrl1 |= (msg->size - 1) << SP_AUX_LENGTH_SHIFT;
> +
> +	if ((msg->request & DP_AUX_I2C_READ) == 0) {
> +		/* When WRITE | MOT write values to data buffer */
> +		err = regmap_bulk_write(map_dptx,
> +					SP_DP_BUF_DATA0_REG, buffer,
> +					msg->size);
> +		if (err)
> +			return err;
> +	}
> +
> +	/* Write address and request */
> +	err = anx_aux_address(map_dptx, msg->address);
> +	if (err)
> +		return err;
> +
> +	err = regmap_write(map_dptx, SP_DP_AUX_CH_CTRL1_REG, ctrl1);
> +	if (err)
> +		return err;
> +
> +	/* Start transaction */
> +	err = regmap_update_bits(map_dptx, SP_DP_AUX_CH_CTRL2_REG,
> +				 SP_ADDR_ONLY | SP_AUX_EN, ctrl2);
> +	if (err)
> +		return err;
> +
> +	err = anx_aux_wait(map_dptx);
> +	if (err)
> +		return err;
> +
> +	msg->reply = DP_AUX_I2C_REPLY_ACK;
> +
> +	if ((msg->size > 0) && (msg->request & DP_AUX_I2C_READ)) {
> +		/* Read values from data buffer */
> +		err = regmap_bulk_read(map_dptx,
> +				       SP_DP_BUF_DATA0_REG, buffer,
> +				       msg->size);
> +		if (err)
> +			return err;
> +	}
> +
> +	err = anx_clear_bits(map_dptx, SP_DP_AUX_CH_CTRL2_REG, SP_ADDR_ONLY);
> +	if (err)
> +		return err;
> +
> +	return msg->size;
> +}
> +EXPORT_SYMBOL(anx_aux_transfer);

As the code license is GPL and the analogic DP core core is exported
with EXPORT_SYMBOL_GPL, should it be the case here too ?

> +
> +MODULE_DESCRIPTION("Analogix DisplayPort Transmitter common code");
> +MODULE_AUTHOR("Icenowy Zheng <icenowy@aosc.io>");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.h b/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.h
> index bc0831b127bf..c2ca854613a0 100644
> --- a/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.h
> +++ b/drivers/gpu/drm/bridge/analogix/analogix-i2c-dptx.h
> @@ -245,4 +245,6 @@
>  /* DP AUX Buffer Data Registers */
>  #define SP_DP_BUF_DATA0_REG		0xf0
>  
> +ssize_t anx_aux_transfer(struct regmap *map_dptx, struct drm_dp_aux_msg *msg);

The name is a bit generic, should it be anx_dp_aux_transfer() ?

> +
>  #endif

-- 
Regards,

Laurent Pinchart