mfd: lpc_ich: Add support for Intel Apollo Lake SoC

Intel Apollo Lake SoC exposes serial SPI flash through the LPC device. The
SPI flash host controller is not discoverable through PCI config cycles
because P2SB (function 0 of the device 13) is hidden by the BIOS. We unhide
the device briefly in order to read BAR 0 of the SPI host controller.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/lpc_ich.c

@@ -56,6 +56,7 @@
  *	document number TBD : Wildcat Point-LP
  *	document number TBD : 9 Series
  *	document number TBD : Lewisburg
+ *	document number TBD : Apollo Lake SoC
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
@@ -92,6 +93,8 @@
 #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
@@ -239,6 +242,7 @@ enum lpc_chipsets {
 	LPC_BRASWELL,	/* Braswell SoC */
 	LPC_LEWISBURG,	/* Lewisburg */
 	LPC_9S,		/* 9 Series */
+	LPC_APL,	/* Apollo Lake SoC */
 };
 
 static struct lpc_ich_info lpc_chipset_info[] = {
@@ -561,6 +565,10 @@ static struct lpc_ich_info lpc_chipset_info[] = {
 		.iTCO_version = 2,
 		.gpio_version = ICH_V5_GPIO,
 	},
+	[LPC_APL] = {
+		.name = "Apollo Lake SoC",
+		.spi_type = INTEL_SPI_BXT,
+	},
 };
 
 /*
@@ -709,6 +717,7 @@ static const struct pci_device_id lpc_ich_ids[] = {
 	{ PCI_VDEVICE(INTEL, 0x3b14), LPC_3420},
 	{ PCI_VDEVICE(INTEL, 0x3b16), LPC_3450},
 	{ PCI_VDEVICE(INTEL, 0x5031), LPC_EP80579},
+	{ PCI_VDEVICE(INTEL, 0x5ae8), LPC_APL},
 	{ PCI_VDEVICE(INTEL, 0x8c40), LPC_LPT},
 	{ PCI_VDEVICE(INTEL, 0x8c41), LPC_LPT},
 	{ PCI_VDEVICE(INTEL, 0x8c42), LPC_LPT},
@@ -1128,6 +1137,36 @@ 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;
+
+		/*
+		 * 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;
+
+			pci_bus_read_config_dword(bus, spi, BCR, &bcr);
+			if (!(bcr & BCR_WPD)) {
+				bcr |= BCR_WPD;
+				pci_bus_write_config_dword(bus, spi, BCR, bcr);
+				pci_bus_read_config_dword(bus, spi, BCR, &bcr);
+			}
+			info->writeable = !!(bcr & BCR_WPD);
+		}
+
+		pci_bus_write_config_byte(bus, p2sb, 0xe1, 0x1);
+		break;
+	}
+
 	default:
 		return -EINVAL;
 	}