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

[Serge Semin <Sergey.Semin@baikalelectronics.ru>]

On Wed, May 27, 2020 at 05:03:03PM +0300, Andy Shevchenko wrote:
> 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,

Well, solution with glue-layers I liked more than this one. If your were
talking regarding the regmap conversion itself. I admit, it's neater.)

-Sergey

> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> 
> > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> > Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
> > Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> > Cc: Rob Herring <robh+dt@kernel.org>
> > Cc: linux-mips@vger.kernel.org
> > Cc: devicetree@vger.kernel.org
> > 
> > ---
> > 
> > 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
> 
>