mfd: lpc_ich: Add support for SPI serial flash host controller

Many Intel CPUs including Haswell, Broadwell and Baytrail have SPI serial
flash host controller as part of the LPC device. This will populate an MFD
cell suitable for the SPI host controller driver if we know that the LPC
device has one.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/lpc_ich.c

@@ -83,6 +83,15 @@
 #define ACPIBASE_GCS_OFF	0x3410
 #define ACPIBASE_GCS_END	0x3414
 
+#define SPIBASE_BYT		0x54
+#define SPIBASE_BYT_SZ		512
+#define SPIBASE_BYT_EN		BIT(1)
+
+#define SPIBASE_LPT		0x3800
+#define SPIBASE_LPT_SZ		512
+#define BCR			0xdc
+#define BCR_WPD			BIT(0)
+
 #define GPIOBASE_ICH0		0x58
 #define GPIOCTRL_ICH0		0x5C
 #define GPIOBASE_ICH6		0x48
@@ -133,6 +142,12 @@ static struct resource gpio_ich_res[] = {
 	},
 };
 
+static struct resource intel_spi_res[] = {
+	{
+		.flags = IORESOURCE_MEM,
+	}
+};
+
 static struct mfd_cell lpc_ich_wdt_cell = {
 	.name = "iTCO_wdt",
 	.num_resources = ARRAY_SIZE(wdt_ich_res),
@@ -147,6 +162,14 @@ static struct mfd_cell lpc_ich_gpio_cell = {
 	.ignore_resource_conflicts = true,
 };
 
+
+static struct mfd_cell lpc_ich_spi_cell = {
+	.name = "intel-spi",
+	.num_resources = ARRAY_SIZE(intel_spi_res),
+	.resources = intel_spi_res,
+	.ignore_resource_conflicts = true,
+};
+
 /* chipset related info */
 enum lpc_chipsets {
 	LPC_ICH = 0,	/* ICH */
@@ -494,10 +517,12 @@ static struct lpc_ich_info lpc_chipset_info[] = {
 		.name = "Lynx Point",
 		.iTCO_version = 2,
 		.gpio_version = ICH_V5_GPIO,
+		.spi_type = INTEL_SPI_LPT,
 	},
 	[LPC_LPT_LP] = {
 		.name = "Lynx Point_LP",
 		.iTCO_version = 2,
+		.spi_type = INTEL_SPI_LPT,
 	},
 	[LPC_WBG] = {
 		.name = "Wellsburg",
@@ -511,6 +536,7 @@ static struct lpc_ich_info lpc_chipset_info[] = {
 	[LPC_BAYTRAIL] = {
 		.name = "Bay Trail SoC",
 		.iTCO_version = 3,
+		.spi_type = INTEL_SPI_BYT,
 	},
 	[LPC_COLETO] = {
 		.name = "Coleto Creek",
@@ -519,10 +545,12 @@ static struct lpc_ich_info lpc_chipset_info[] = {
 	[LPC_WPT_LP] = {
 		.name = "Wildcat Point_LP",
 		.iTCO_version = 2,
+		.spi_type = INTEL_SPI_LPT,
 	},
 	[LPC_BRASWELL] = {
 		.name = "Braswell SoC",
 		.iTCO_version = 3,
+		.spi_type = INTEL_SPI_BYT,
 	},
 	[LPC_LEWISBURG] = {
 		.name = "Lewisburg",
@@ -1056,6 +1084,64 @@ static int lpc_ich_init_wdt(struct pci_dev *dev)
 	return ret;
 }
 
+static int lpc_ich_init_spi(struct pci_dev *dev)
+{
+	struct lpc_ich_priv *priv = pci_get_drvdata(dev);
+	struct resource *res = &intel_spi_res[0];
+	struct intel_spi_boardinfo *info;
+	u32 spi_base, rcba, bcr;
+
+	info = devm_kzalloc(&dev->dev, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	info->type = lpc_chipset_info[priv->chipset].spi_type;
+
+	switch (info->type) {
+	case INTEL_SPI_BYT:
+		pci_read_config_dword(dev, SPIBASE_BYT, &spi_base);
+		if (spi_base & SPIBASE_BYT_EN) {
+			res->start = spi_base & ~(SPIBASE_BYT_SZ - 1);
+			res->end = res->start + SPIBASE_BYT_SZ - 1;
+		}
+		break;
+
+	case INTEL_SPI_LPT:
+		pci_read_config_dword(dev, RCBABASE, &rcba);
+		if (rcba & 1) {
+			spi_base = round_down(rcba, SPIBASE_LPT_SZ);
+			res->start = spi_base + SPIBASE_LPT;
+			res->end = res->start + SPIBASE_LPT_SZ - 1;
+
+			/*
+			 * Try to make the flash chip writeable now by
+			 * setting BCR_WPD. It it fails we tell the driver
+			 * that it can only read the chip.
+			 */
+			pci_read_config_dword(dev, BCR, &bcr);
+			if (!(bcr & BCR_WPD)) {
+				bcr |= BCR_WPD;
+				pci_write_config_dword(dev, BCR, bcr);
+				pci_read_config_dword(dev, BCR, &bcr);
+			}
+			info->writeable = !!(bcr & BCR_WPD);
+		}
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	if (!res->start)
+		return -ENODEV;
+
+	lpc_ich_spi_cell.platform_data = info;
+	lpc_ich_spi_cell.pdata_size = sizeof(*info);
+
+	return mfd_add_devices(&dev->dev, PLATFORM_DEVID_NONE,
+			       &lpc_ich_spi_cell, 1, NULL, 0, NULL);
+}
+
 static int lpc_ich_probe(struct pci_dev *dev,
 				const struct pci_device_id *id)
 {
@@ -1099,6 +1185,12 @@ static int lpc_ich_probe(struct pci_dev *dev,
 			cell_added = true;
 	}
 
+	if (lpc_chipset_info[priv->chipset].spi_type) {
+		ret = lpc_ich_init_spi(dev);
+		if (!ret)
+			cell_added = true;
+	}
+
 	/*
 	 * We only care if at least one or none of the cells registered
 	 * successfully.

include/linux/mfd/lpc_ich.h

@@ -20,6 +20,8 @@
 #ifndef LPC_ICH_H
 #define LPC_ICH_H
 
+#include <linux/platform_data/intel-spi.h>
+
 /* GPIO resources */
 #define ICH_RES_GPIO	0
 #define ICH_RES_GPE0	1
@@ -40,6 +42,7 @@ struct lpc_ich_info {
 	char name[32];
 	unsigned int iTCO_version;
 	unsigned int gpio_version;
+	enum intel_spi_type spi_type;
 	u8 use_gpio;
 };