Re: [PATCH v5 3/4] Watchdog: sp5100_tco: Add initialization using EFCH MMIO

[Guenter Roeck <linux@roeck-us.net>]

On Wed, Feb 02, 2022 at 09:35:24AM -0600, Terry Bowman wrote:
> cd6h/cd7h port I/O can be disabled on recent AMD hardware. Read
> accesses to disabled cd6h/cd7h port I/O will return F's and written
> data is dropped. It is recommended to replace the cd6h/cd7h
> port I/O with MMIO.
> 
> Co-developed-by: Robert Richter <rrichter@amd.com>
> Signed-off-by: Robert Richter <rrichter@amd.com>
> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
> Tested-by: Jean Delvare <jdelvare@suse.de>
> Reviewed-by: Jean Delvare <jdelvare@suse.de>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
>  drivers/watchdog/sp5100_tco.c | 100 +++++++++++++++++++++++++++++++++-
>  drivers/watchdog/sp5100_tco.h |   5 ++
>  2 files changed, 104 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/watchdog/sp5100_tco.c b/drivers/watchdog/sp5100_tco.c
> index 8db7504f0aa4..e02399ea8730 100644
> --- a/drivers/watchdog/sp5100_tco.c
> +++ b/drivers/watchdog/sp5100_tco.c
> @@ -49,7 +49,7 @@
>  /* internal variables */
>  
>  enum tco_reg_layout {
> -	sp5100, sb800, efch
> +	sp5100, sb800, efch, efch_mmio
>  };
>  
>  struct sp5100_tco {
> @@ -209,6 +209,8 @@ static void tco_timer_enable(struct sp5100_tco *tco)
>  					  ~EFCH_PM_WATCHDOG_DISABLE,
>  					  EFCH_PM_DECODEEN_SECOND_RES);
>  		break;
> +	default:
> +		break;
>  	}
>  }
>  
> @@ -307,6 +309,99 @@ static int sp5100_tco_timer_init(struct sp5100_tco *tco)
>  	return 0;
>  }
>  
> +static u8 efch_read_pm_reg8(void __iomem *addr, u8 index)
> +{
> +	return readb(addr + index);
> +}
> +
> +static void efch_update_pm_reg8(void __iomem *addr, u8 index, u8 reset, u8 set)
> +{
> +	u8 val;
> +
> +	val = readb(addr + index);
> +	val &= reset;
> +	val |= set;
> +	writeb(val, addr + index);
> +}
> +
> +static void tco_timer_enable_mmio(void __iomem *addr)
> +{
> +	efch_update_pm_reg8(addr, EFCH_PM_DECODEEN3,
> +			    ~EFCH_PM_WATCHDOG_DISABLE,
> +			    EFCH_PM_DECODEEN_SECOND_RES);
> +}
> +
> +static int sp5100_tco_setupdevice_mmio(struct device *dev,
> +				       struct watchdog_device *wdd)
> +{
> +	struct sp5100_tco *tco = watchdog_get_drvdata(wdd);
> +	const char *dev_name = SB800_DEVNAME;
> +	u32 mmio_addr = 0, alt_mmio_addr = 0;
> +	struct resource *res;
> +	void __iomem *addr;
> +	int ret;
> +	u32 val;
> +
> +	res = request_mem_region_muxed(EFCH_PM_ACPI_MMIO_PM_ADDR,
> +				       EFCH_PM_ACPI_MMIO_PM_SIZE,
> +				       "sp5100_tco");
> +
> +	if (!res) {
> +		dev_err(dev,
> +			"Memory region 0x%08x already in use\n",
> +			EFCH_PM_ACPI_MMIO_PM_ADDR);
> +		return -EBUSY;
> +	}
> +
> +	addr = ioremap(EFCH_PM_ACPI_MMIO_PM_ADDR, EFCH_PM_ACPI_MMIO_PM_SIZE);
> +	if (!addr) {
> +		dev_err(dev, "Address mapping failed\n");
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +
> +	/*
> +	 * EFCH_PM_DECODEEN_WDT_TMREN is dual purpose. This bitfield
> +	 * enables sp5100_tco register MMIO space decoding. The bitfield
> +	 * also starts the timer operation. Enable if not already enabled.
> +	 */
> +	val = efch_read_pm_reg8(addr, EFCH_PM_DECODEEN);
> +	if (!(val & EFCH_PM_DECODEEN_WDT_TMREN)) {
> +		efch_update_pm_reg8(addr, EFCH_PM_DECODEEN, 0xff,
> +				    EFCH_PM_DECODEEN_WDT_TMREN);
> +	}
> +
> +	/* Error if the timer could not be enabled */
> +	val = efch_read_pm_reg8(addr, EFCH_PM_DECODEEN);
> +	if (!(val & EFCH_PM_DECODEEN_WDT_TMREN)) {
> +		dev_err(dev, "Failed to enable the timer\n");
> +		ret = -EFAULT;
> +		goto out;
> +	}
> +
> +	mmio_addr = EFCH_PM_WDT_ADDR;
> +
> +	/* Determine alternate MMIO base address */
> +	val = efch_read_pm_reg8(addr, EFCH_PM_ISACONTROL);
> +	if (val & EFCH_PM_ISACONTROL_MMIOEN)
> +		alt_mmio_addr = EFCH_PM_ACPI_MMIO_ADDR +
> +			EFCH_PM_ACPI_MMIO_WDT_OFFSET;
> +
> +	ret = sp5100_tco_prepare_base(tco, mmio_addr, alt_mmio_addr, dev_name);
> +	if (!ret) {
> +		tco_timer_enable_mmio(addr);
> +		ret = sp5100_tco_timer_init(tco);
> +	}
> +
> +out:
> +	if (addr)
> +		iounmap(addr);
> +
> +	release_resource(res);
> +
> +	return ret;
> +}
> +
>  static int sp5100_tco_setupdevice(struct device *dev,
>  				  struct watchdog_device *wdd)
>  {
> @@ -316,6 +411,9 @@ static int sp5100_tco_setupdevice(struct device *dev,
>  	u32 alt_mmio_addr = 0;
>  	int ret;
>  
> +	if (tco->tco_reg_layout == efch_mmio)
> +		return sp5100_tco_setupdevice_mmio(dev, wdd);
> +
>  	/* Request the IO ports used by this driver */
>  	if (!request_muxed_region(SP5100_IO_PM_INDEX_REG,
>  				  SP5100_PM_IOPORTS_SIZE, "sp5100_tco")) {
> diff --git a/drivers/watchdog/sp5100_tco.h b/drivers/watchdog/sp5100_tco.h
> index daee872f9b71..8ca1b215e3ce 100644
> --- a/drivers/watchdog/sp5100_tco.h
> +++ b/drivers/watchdog/sp5100_tco.h
> @@ -83,4 +83,9 @@
>  #define EFCH_PM_ISACONTROL_MMIOEN	BIT(1)
>  
>  #define EFCH_PM_ACPI_MMIO_ADDR		0xfed80000
> +#define EFCH_PM_ACPI_MMIO_PM_OFFSET	0x00000300
>  #define EFCH_PM_ACPI_MMIO_WDT_OFFSET	0x00000b00
> +
> +#define EFCH_PM_ACPI_MMIO_PM_ADDR	(EFCH_PM_ACPI_MMIO_ADDR +	\
> +					 EFCH_PM_ACPI_MMIO_PM_OFFSET)
> +#define EFCH_PM_ACPI_MMIO_PM_SIZE	8
> -- 
> 2.30.2
>