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Date: Thu, 6 Jan 2022 10:18:09 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Terry Bowman <terry.bowman@....com>
Cc: linux-watchdog@...r.kernel.org, rrichter@....com,
linux-kernel@...r.kernel.org, wim@...ux-watchdog.org,
ssg.sos.patches@....com, sudheesh.mavila@....com
Subject: Re: [PATCH v2 3/4] Watchdog: sp5100_tco: Add EFCH SMBus controller
initialization using MMIO
On Wed, Nov 03, 2021 at 11:15:20AM -0500, 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.
>
> The recommended workaround to handle disabled cd6h/cd7h port I/O is
> replacing port I/O with MMIO accesses. The MMIO access method has been
> available since at least SMBus controllers using PCI revision 0x59.
>
> The EFCH MMIO path is enabled in later patch.
>
> Co-developed-by: Robert Richter <rrichter@....com>
> Signed-off-by: Robert Richter <rrichter@....com>
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> To: linux-watchdog@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Cc: Wim Van Sebroeck <wim@...ux-watchdog.org>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: Robert Richter <rrichter@....com>
> ---
> drivers/watchdog/sp5100_tco.c | 104 +++++++++++++++++++++++++++++++++-
> drivers/watchdog/sp5100_tco.h | 6 ++
> 2 files changed, 109 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/watchdog/sp5100_tco.c b/drivers/watchdog/sp5100_tco.c
> index 80ae42ae7aaa..4777e672a8ad 100644
> --- a/drivers/watchdog/sp5100_tco.c
> +++ b/drivers/watchdog/sp5100_tco.c
> @@ -48,12 +48,14 @@
> /* internal variables */
>
> enum tco_reg_layout {
> - sp5100, sb800, efch
> + sp5100, sb800, efch, efch_mmio
> };
>
> struct sp5100_tco {
> struct watchdog_device wdd;
> void __iomem *tcobase;
> + void __iomem *addr;
> + struct resource *res;
I must admit that I really don't like this code. Both res and
addr are only used during initialization, yet their presence suggests
runtime usage. Any chance to reqork this to not require those variables ?
Guenter
> enum tco_reg_layout tco_reg_layout;
> };
>
> @@ -161,6 +163,59 @@ static void sp5100_tco_update_pm_reg8(u8 index, u8 reset, u8 set)
> outb(val, SP5100_IO_PM_DATA_REG);
> }
>
> +static int sp5100_request_region_mmio(struct device *dev,
> + struct watchdog_device *wdd)
> +{
> + struct sp5100_tco *tco = watchdog_get_drvdata(wdd);
> + struct resource *res;
> + void __iomem *addr;
> +
> + res = request_mem_region(EFCH_PM_ACPI_MMIO_PM_ADDR,
> + EFCH_PM_ACPI_MMIO_PM_SIZE,
> + "sp5100_tco");
> +
> + if (!res) {
> + dev_err(dev,
> + "SMB base address memory region 0x%x 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) {
> + release_resource(res);
> + dev_err(dev, "SMB base address mapping failed.\n");
> + return -ENOMEM;
> + }
> +
> + tco->res = res;
> + tco->addr = addr;
> + return 0;
> +}
> +
> +static void sp5100_release_region_mmio(struct sp5100_tco *tco)
> +{
> + iounmap(tco->addr);
> + release_resource(tco->res);
> +}
> +
> +static u8 efch_read_pm_reg8(struct sp5100_tco *tco, u8 index)
> +{
> + return readb(tco->addr + index);
> +}
> +
> +static void efch_update_pm_reg8(struct sp5100_tco *tco,
> + u8 index, u8 reset, u8 set)
> +{
> + u8 val;
> +
> + val = readb(tco->addr + index);
> + val &= reset;
> + val |= set;
> + writeb(val, tco->addr + index);
> +}
> +
> static void tco_timer_enable(struct sp5100_tco *tco)
> {
> u32 val;
> @@ -201,6 +256,12 @@ static void tco_timer_enable(struct sp5100_tco *tco)
> ~EFCH_PM_WATCHDOG_DISABLE,
> EFCH_PM_DECODEEN_SECOND_RES);
> break;
> + case efch_mmio:
> + /* Set the Watchdog timer resolution to 1 sec and enable */
> + efch_update_pm_reg8(tco, EFCH_PM_DECODEEN3,
> + ~EFCH_PM_WATCHDOG_DISABLE,
> + EFCH_PM_DECODEEN_SECOND_RES);
> + break;
> }
> }
>
> @@ -313,6 +374,44 @@ static int sp5100_tco_timer_init(struct sp5100_tco *tco)
> return 0;
> }
>
> +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;
> + int ret;
> +
> + ret = sp5100_request_region_mmio(dev, wdd);
> + if (ret)
> + return ret;
> +
> + /* Determine MMIO base address */
> + if (!(efch_read_pm_reg8(tco, EFCH_PM_DECODEEN) &
> + EFCH_PM_DECODEEN_WDT_TMREN)) {
> + efch_update_pm_reg8(tco, EFCH_PM_DECODEEN,
> + 0xff,
> + EFCH_PM_DECODEEN_WDT_TMREN);
> + }
> +
> + if (efch_read_pm_reg8(tco, EFCH_PM_DECODEEN) &
> + EFCH_PM_DECODEEN_WDT_TMREN)
> + mmio_addr = EFCH_PM_WDT_ADDR;
> +
> + /* Determine alternate MMIO base address */
> + if (efch_read_pm_reg8(tco, EFCH_PM_ISACONTROL) &
> + 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)
> + ret = sp5100_tco_timer_init(tco);
> +
> + sp5100_release_region_mmio(tco);
> + return ret;
> +}
> +
> static int sp5100_tco_setupdevice(struct device *dev,
> struct watchdog_device *wdd)
> {
> @@ -322,6 +421,9 @@ 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 adf015aa4126..73f179a1d6e5 100644
> --- a/drivers/watchdog/sp5100_tco.h
> +++ b/drivers/watchdog/sp5100_tco.h
> @@ -83,3 +83,9 @@
>
> #define EFCH_PM_ACPI_MMIO_ADDR 0xfed80000
> #define EFCH_PM_ACPI_MMIO_WDT_OFFSET 0x00000b00
> +#define EFCH_PM_ACPI_MMIO_PM_OFFSET 0x00000300
> +
> +#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
> +
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