Re: [PATCH v4 11/11] i2c: designware: Add Baikal-T1 System I2C support

[Andy Shevchenko]

On Wed, May 27, 2020 at 03:01:11PM +0300, Serge Semin wrote:
> Baikal-T1 System Controller is equipped with a dedicated I2C Controller
> which functionality is based on the DW APB I2C IP-core, the only
> difference in a way it' registers are accessed. There are three access
> register provided in the System Controller registers map, which indirectly
> address the normal DW APB I2C registers space. So in order to have the
> Baikal-T1 System I2C Controller supported by the common DW APB I2C driver
> we created a dedicated Dw I2C controller model quirk, which retrieves the
> syscon regmap from the parental dt node and creates a new regmap based on
> it.

Yes, you see how cool it is now! FWIW,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

> Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
> Cc: Alexey Malahov <Alexey.Malahov@xxxxxxxxxxxxxxxxxxxx>
> Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
> Cc: Rob Herring <robh+dt@xxxxxxxxxx>
> Cc: linux-mips@xxxxxxxxxxxxxxx
> Cc: devicetree@xxxxxxxxxxxxxxx
> 
> ---
> 
> Changelog v3:
> - This is a new patch, which has been created due to declining the
>   glue-layer approach.
> 
> Changelog v4:
> - Use PTR_ERR_OR_ZERO() helper in the bt1_i2c_request_regs() method.
> ---
>  drivers/i2c/busses/Kconfig                  |  3 +-
>  drivers/i2c/busses/i2c-designware-core.h    |  3 +
>  drivers/i2c/busses/i2c-designware-platdrv.c | 78 ++++++++++++++++++++-
>  3 files changed, 81 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 259e2325712a..0cf7aea30138 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -541,8 +541,9 @@ config I2C_DESIGNWARE_SLAVE
>  
>  config I2C_DESIGNWARE_PLATFORM
>  	tristate "Synopsys DesignWare Platform"
> -	select I2C_DESIGNWARE_CORE
>  	depends on (ACPI && COMMON_CLK) || !ACPI
> +	select I2C_DESIGNWARE_CORE
> +	select MFD_SYSCON if MIPS_BAIKAL_T1
>  	help
>  	  If you say yes to this option, support will be included for the
>  	  Synopsys DesignWare I2C adapter.
> diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
> index f5bbe3d6bcf8..556673a1f61b 100644
> --- a/drivers/i2c/busses/i2c-designware-core.h
> +++ b/drivers/i2c/busses/i2c-designware-core.h
> @@ -183,6 +183,7 @@ struct reset_control;
>   * struct dw_i2c_dev - private i2c-designware data
>   * @dev: driver model device node
>   * @map: IO registers map
> + * @sysmap: System controller registers map
>   * @base: IO registers pointer
>   * @ext: Extended IO registers pointer
>   * @cmd_complete: tx completion indicator
> @@ -235,6 +236,7 @@ struct reset_control;
>  struct dw_i2c_dev {
>  	struct device		*dev;
>  	struct regmap		*map;
> +	struct regmap		*sysmap;
>  	void __iomem		*base;
>  	void __iomem		*ext;
>  	struct completion	cmd_complete;
> @@ -290,6 +292,7 @@ struct dw_i2c_dev {
>  #define ACCESS_NO_IRQ_SUSPEND	0x00000002
>  
>  #define MODEL_MSCC_OCELOT	0x00000100
> +#define MODEL_BAIKAL_BT1	0x00000200
>  #define MODEL_MASK		0x00000f00
>  
>  int i2c_dw_init_regmap(struct dw_i2c_dev *dev);
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index 061c8d506c7c..d9c5337bb22b 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -18,6 +18,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/kernel.h>
> +#include <linux/mfd/syscon.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/platform_data/i2c-designware.h>
> @@ -25,6 +26,7 @@
>  #include <linux/pm.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/property.h>
> +#include <linux/regmap.h>
>  #include <linux/reset.h>
>  #include <linux/sched.h>
>  #include <linux/slab.h>
> @@ -58,6 +60,63 @@ MODULE_DEVICE_TABLE(acpi, dw_i2c_acpi_match);
>  #endif
>  
>  #ifdef CONFIG_OF
> +#define BT1_I2C_CTL			0x100
> +#define BT1_I2C_CTL_ADDR_MASK		GENMASK(7, 0)
> +#define BT1_I2C_CTL_WR			BIT(8)
> +#define BT1_I2C_CTL_GO			BIT(31)
> +#define BT1_I2C_DI			0x104
> +#define BT1_I2C_DO			0x108
> +
> +static int bt1_i2c_read(void *context, unsigned int reg, unsigned int *val)
> +{
> +	struct dw_i2c_dev *dev = context;
> +	int ret;
> +
> +	/*
> +	 * Note these methods shouldn't ever fail because the system controller
> +	 * registers are memory mapped. We check the return value just in case.
> +	 */
> +	ret = regmap_write(dev->sysmap, BT1_I2C_CTL,
> +			   BT1_I2C_CTL_GO | (reg & BT1_I2C_CTL_ADDR_MASK));
> +	if (ret)
> +		return ret;
> +
> +	return regmap_read(dev->sysmap, BT1_I2C_DO, val);
> +}
> +
> +static int bt1_i2c_write(void *context, unsigned int reg, unsigned int val)
> +{
> +	struct dw_i2c_dev *dev = context;
> +	int ret;
> +
> +	ret = regmap_write(dev->sysmap, BT1_I2C_DI, val);
> +	if (ret)
> +		return ret;
> +
> +	return regmap_write(dev->sysmap, BT1_I2C_CTL,
> +		BT1_I2C_CTL_GO | BT1_I2C_CTL_WR | (reg & BT1_I2C_CTL_ADDR_MASK));
> +}
> +
> +static struct regmap_config bt1_i2c_cfg = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +	.fast_io = true,
> +	.reg_read = bt1_i2c_read,
> +	.reg_write = bt1_i2c_write,
> +	.max_register = DW_IC_COMP_TYPE
> +};
> +
> +static int bt1_i2c_request_regs(struct dw_i2c_dev *dev)
> +{
> +	dev->sysmap = syscon_node_to_regmap(dev->dev->of_node->parent);
> +	if (IS_ERR(dev->sysmap))
> +		return PTR_ERR(dev->sysmap);
> +
> +	dev->map = devm_regmap_init(dev->dev, NULL, dev, &bt1_i2c_cfg);
> +	return PTR_ERR_OR_ZERO(dev->map);
> +}
> +
>  #define MSCC_ICPU_CFG_TWI_DELAY		0x0
>  #define MSCC_ICPU_CFG_TWI_DELAY_ENABLE	BIT(0)
>  #define MSCC_ICPU_CFG_TWI_SPIKE_FILTER	0x4
> @@ -90,10 +149,16 @@ static int dw_i2c_of_configure(struct platform_device *pdev)
>  static const struct of_device_id dw_i2c_of_match[] = {
>  	{ .compatible = "snps,designware-i2c", },
>  	{ .compatible = "mscc,ocelot-i2c", .data = (void *)MODEL_MSCC_OCELOT },
> +	{ .compatible = "baikal,bt1-sys-i2c", .data = (void *)MODEL_BAIKAL_BT1 },
>  	{},
>  };
>  MODULE_DEVICE_TABLE(of, dw_i2c_of_match);
>  #else
> +static int bt1_i2c_request_regs(struct dw_i2c_dev *dev)
> +{
> +	return -ENODEV;
> +}
> +
>  static inline int dw_i2c_of_configure(struct platform_device *pdev)
>  {
>  	return -ENODEV;
> @@ -111,10 +176,19 @@ static void dw_i2c_plat_pm_cleanup(struct dw_i2c_dev *dev)
>  static int dw_i2c_plat_request_regs(struct dw_i2c_dev *dev)
>  {
>  	struct platform_device *pdev = to_platform_device(dev->dev);
> +	int ret;
>  
> -	dev->base = devm_platform_ioremap_resource(pdev, 0);
> +	switch (dev->flags & MODEL_MASK) {
> +	case MODEL_BAIKAL_BT1:
> +		ret = bt1_i2c_request_regs(dev);
> +		break;
> +	default:
> +		dev->base = devm_platform_ioremap_resource(pdev, 0);
> +		ret = PTR_ERR_OR_ZERO(dev->base);
> +		break;
> +	}
>  
> -	return PTR_ERR_OR_ZERO(dev->base);
> +	return ret;
>  }
>  
>  static int dw_i2c_plat_probe(struct platform_device *pdev)
> -- 
> 2.26.2
> 

-- 
With Best Regards,
Andy Shevchenko