[PATCH v3 3/4] Watchdog: sp5100_tco: Add initialization using EFCH MMIO

[Terry Bowman <terry.bowman@amd.com>]

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>
To: Guenter Roeck <linux@roeck-us.net>
To: linux-watchdog@vger.kernel.org
To: Jean Delvare <jdelvare@suse.com>
To: linux-i2c@vger.kernel.org
To: Wolfram Sang <wsa@kernel.org>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: linux-kernel@vger.kernel.org
Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Robert Richter <rrichter@amd.com>
Cc: Thomas Lendacky <thomas.lendacky@amd.com>
---
 drivers/watchdog/sp5100_tco.c | 88 ++++++++++++++++++++++++++++++++++-
 drivers/watchdog/sp5100_tco.h |  5 ++
 2 files changed, 92 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/sp5100_tco.c b/drivers/watchdog/sp5100_tco.c
index 64ecebd93403..36519a992ca1 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;
 	}
 }
 
@@ -318,6 +320,87 @@ 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;
+
+	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;
+	}
+
+	if (!(efch_read_pm_reg8(addr, EFCH_PM_DECODEEN) &
+	      EFCH_PM_DECODEEN_WDT_TMREN)) {
+		efch_update_pm_reg8(addr, EFCH_PM_DECODEEN,
+				    0xff,
+				    EFCH_PM_DECODEEN_WDT_TMREN);
+	}
+
+	/* Determine MMIO base address */
+	if (efch_read_pm_reg8(addr, EFCH_PM_DECODEEN) &
+	    EFCH_PM_DECODEEN_WDT_TMREN)
+		mmio_addr = EFCH_PM_WDT_ADDR;
+
+	/* Determine alternate MMIO base address */
+	if (efch_read_pm_reg8(addr, 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) {
+		tco_timer_enable_mmio(addr);
+		ret = sp5100_tco_timer_init(tco);
+	}
+
+	iounmap(addr);
+	release_resource(res);
+
+	return ret;
+}
+
 static int sp5100_tco_setupdevice(struct device *dev,
 				  struct watchdog_device *wdd)
 {
@@ -327,6 +410,9 @@ 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..2df8f8b2c55b 100644
--- a/drivers/watchdog/sp5100_tco.h
+++ b/drivers/watchdog/sp5100_tco.h
@@ -83,3 +83,8 @@
 
 #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
-- 
2.30.2