mfd: lpc_ich: Switch to generic p2sb_bar()

Instead of open coding p2sb_bar() functionality we are going to
use generic library. There is one more user en route.

This is more than just a clean-up. It also fixes a potential issue
seen when SPI BAR is 64-bit. The current code works if and only if
the PCI BAR of the hidden device is inside 4G address space. In case
when firmware decides to go above 4G, we will get a wrong address.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Henning Schild <henning.schild@siemens.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>

drivers/mfd/Kconfig

@@ -572,6 +572,7 @@ config LPC_ICH
 	tristate "Intel ICH LPC"
 	depends on PCI
 	select MFD_CORE
+	select P2SB if X86
 	help
 	  The LPC bridge function of the Intel ICH provides support for
 	  many functional units. This driver provides needed support for

drivers/mfd/lpc_ich.c

@@ -45,6 +45,7 @@
 #include <linux/mfd/core.h>
 #include <linux/mfd/lpc_ich.h>
 #include <linux/platform_data/itco_wdt.h>
+#include <linux/platform_data/x86/p2sb.h>
 
 #define ACPIBASE		0x40
 #define ACPIBASE_GPE_OFF	0x28
@@ -71,8 +72,6 @@
 #define BCR			0xdc
 #define BCR_WPD			BIT(0)
 
-#define SPIBASE_APL_SZ		4096
-
 #define GPIOBASE_ICH0		0x58
 #define GPIOCTRL_ICH0		0x5C
 #define GPIOBASE_ICH6		0x48
@@ -1134,6 +1133,7 @@ static int lpc_ich_init_spi(struct pci_dev *dev)
 	struct resource *res = &intel_spi_res[0];
 	struct intel_spi_boardinfo *info;
 	u32 spi_base, rcba;
+	int ret;
 
 	info = devm_kzalloc(&dev->dev, sizeof(*info), GFP_KERNEL);
 	if (!info)
@@ -1164,30 +1164,19 @@ static int lpc_ich_init_spi(struct pci_dev *dev)
 		}
 		break;
 
-	case INTEL_SPI_BXT: {
-		unsigned int p2sb = PCI_DEVFN(13, 0);
-		unsigned int spi = PCI_DEVFN(13, 2);
-		struct pci_bus *bus = dev->bus;
-
+	case INTEL_SPI_BXT:
 		/*
 		 * The P2SB is hidden by BIOS and we need to unhide it in
 		 * order to read BAR of the SPI flash device. Once that is
 		 * done we hide it again.
 		 */
-		pci_bus_write_config_byte(bus, p2sb, 0xe1, 0x0);
-		pci_bus_read_config_dword(bus, spi, PCI_BASE_ADDRESS_0,
-					  &spi_base);
-		if (spi_base != ~0) {
-			res->start = spi_base & 0xfffffff0;
-			res->end = res->start + SPIBASE_APL_SZ - 1;
-
-			info->set_writeable = lpc_ich_bxt_set_writeable;
-			info->data = dev;
-		}
+		ret = p2sb_bar(dev->bus, PCI_DEVFN(13, 2), res);
+		if (ret)
+			return ret;
 
-		pci_bus_write_config_byte(bus, p2sb, 0xe1, 0x1);
+		info->set_writeable = lpc_ich_bxt_set_writeable;
+		info->data = dev;
 		break;
-	}
 
 	default:
 		return -EINVAL;