diff mbox series

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

Message ID 20220118202234.410555-4-terry.bowman@amd.com (mailing list archive)
State Superseded
Headers show
Series Watchdog: sp5100_tco: Replace cd6h/cd7h port I/O accesses with MMIO accesses | expand

Commit Message

Bowman, Terry Jan. 18, 2022, 8:22 p.m. UTC
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(-)

Comments

Jean Delvare Jan. 24, 2022, 5:36 p.m. UTC | #1
Hi Terry,

On Tue, 18 Jan 2022 14:22:33 -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>
> 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",

SMB -> SMBus

> +			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");

SMB -> SMBus

> +		return -ENOMEM;
> +	}
> +

A short comment saying what the next command is doing would be
appreciated.

> +	if (!(efch_read_pm_reg8(addr, EFCH_PM_DECODEEN) &
> +	      EFCH_PM_DECODEEN_WDT_TMREN)) {

I find such splits hard to read. If checkpatch complains when you don't
split it (but I think it no longer does, right?) then just introduce a
local variable to store the register value. Same for the 2 occurrences
below.

> +		efch_update_pm_reg8(addr, EFCH_PM_DECODEEN,
> +				    0xff,
> +				    EFCH_PM_DECODEEN_WDT_TMREN);

Easily fits in one fewer line.

> +	}
> +
> +	/* 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

Other than these minor details, patch looks good to me, thanks.

Tested-by: Jean Delvare <jdelvare@suse.de>
Bowman, Terry Jan. 24, 2022, 7:20 p.m. UTC | #2
On 1/24/22 11:36 AM, Jean Delvare wrote:
...
>> +	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",
> 
> SMB -> SMBus
> 

Yes, I will update.

>> +			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");
> 
> SMB -> SMBus
> 

Yes, I will update.

>> +		return -ENOMEM;
>> +	}
>> +
> 
> A short comment saying what the next command is doing would be
> appreciated.
> 

I will add a brief comment explaining.

>> +	if (!(efch_read_pm_reg8(addr, EFCH_PM_DECODEEN) &
>> +	      EFCH_PM_DECODEEN_WDT_TMREN)) {
> 
> I find such splits hard to read. If checkpatch complains when you don't
> split it (but I think it no longer does, right?) then just introduce a
> local variable to store the register value. Same for the 2 occurrences
> below.
> 

I will update for readability.

>> +		efch_update_pm_reg8(addr, EFCH_PM_DECODEEN,
>> +				    0xff,
>> +				    EFCH_PM_DECODEEN_WDT_TMREN);
> 
> Easily fits in one fewer line.
> 

I will change to 2 lines.

>> +	}
>> +
>> +	/* 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
> 
> Other than these minor details, patch looks good to me, thanks.
> 
> Tested-by: Jean Delvare <jdelvare@suse.de>
> 

I'm finishing up revisions for this and the i2c patch. I expect to send both tomorrow.

Regards,
Teryr
Bowman, Terry Jan. 24, 2022, 10:36 p.m. UTC | #3
On 1/24/22 11:36 AM, Jean Delvare wrote:
> Hi Terry,
> 
> On Tue, 18 Jan 2022 14:22:33 -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>
>> 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",
> 
> SMB -> SMBus
> 
>> +			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");
> 
> SMB -> SMBus
> 
>> +		return -ENOMEM;
>> +	}
>> +
> 
> A short comment saying what the next command is doing would be
> appreciated.
> 
>> +	if (!(efch_read_pm_reg8(addr, EFCH_PM_DECODEEN) &
>> +	      EFCH_PM_DECODEEN_WDT_TMREN)) {
> 
> I find such splits hard to read. If checkpatch complains when you don't
> split it (but I think it no longer does, right?) then just introduce a
> local variable to store the register value. Same for the 2 occurrences
> below.
> 
>> +		efch_update_pm_reg8(addr, EFCH_PM_DECODEEN,
>> +				    0xff,
>> +				    EFCH_PM_DECODEEN_WDT_TMREN);
> 
> Easily fits in one fewer line.
> 
>> +	}
>> +
>> +	/* 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
> 
> Other than these minor details, patch looks good to me, thanks.
> 
> Tested-by: Jean Delvare <jdelvare@suse.de>
> 

Hi Jean,

Is your "Tested-by" for patch 3/4 or the sp5100_tco series?

Regards,
Terry
Jean Delvare Jan. 25, 2022, 12:42 p.m. UTC | #4
On Mon, 24 Jan 2022 16:36:33 -0600, Terry Bowman wrote:
> Is your "Tested-by" for patch 3/4 or the sp5100_tco series?

For the whole series actually, I only tested with all patches applied,
not the individual patches.
diff mbox series

Patch

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