mtd: spi-nor: intel-spi: Disable write protection only if asked

Currently the driver tries to disable the BIOS write protection
automatically even if this is not what the user wants. For this reason
modify the driver so that by default it does not touch the write
protection. Only if specifically asked by the user (setting writeable=1
command line parameter) the driver tries to disable the BIOS write
protection.

Signed-off-by: Mika Westerberg <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Reviewed-by: Mauro Lima <[e-mail]>
Reviewed-by: Tudor Ambarus <[e-mail]>
Acked-by: Lee Jones <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

drivers/mfd/lpc_ich.c

···
 #define SPIBASE_BYT		0x54
 #define SPIBASE_BYT_SZ		512
 #define SPIBASE_BYT_EN		BIT(1)
+#define BYT_BCR			0xfc
+#define BYT_BCR_WPD		BIT(0)
 
 #define SPIBASE_LPT		0x3800
 #define SPIBASE_LPT_SZ		512
···
 	return ret;
 }
 
+static bool lpc_ich_byt_set_writeable(void __iomem *base, void *data)
+{
+	u32 val;
+
+	val = readl(base + BYT_BCR);
+	if (!(val & BYT_BCR_WPD)) {
+		val |= BYT_BCR_WPD;
+		writel(val, base + BYT_BCR);
+		val = readl(base + BYT_BCR);
+	}
+
+	return val & BYT_BCR_WPD;
+}
+
+static bool lpc_ich_lpt_set_writeable(void __iomem *base, void *data)
+{
+	struct pci_dev *pdev = data;
+	u32 bcr;
+
+	pci_read_config_dword(pdev, BCR, &bcr);
+	if (!(bcr & BCR_WPD)) {
+		bcr |= BCR_WPD;
+		pci_write_config_dword(pdev, BCR, bcr);
+		pci_read_config_dword(pdev, BCR, &bcr);
+	}
+
+	return bcr & BCR_WPD;
+}
+
+static bool lpc_ich_bxt_set_writeable(void __iomem *base, void *data)
+{
+	unsigned int spi = PCI_DEVFN(13, 2);
+	struct pci_bus *bus = data;
+	u32 bcr;
+
+	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);
+	}
+
+	return bcr & BCR_WPD;
+}
+
 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;
+	u32 spi_base, rcba;
 
 	info = devm_kzalloc(&dev->dev, sizeof(*info), GFP_KERNEL);
 	if (!info)
···
 		if (spi_base & SPIBASE_BYT_EN) {
 			res->start = spi_base & ~(SPIBASE_BYT_SZ - 1);
 			res->end = res->start + SPIBASE_BYT_SZ - 1;
+
+			info->set_writeable = lpc_ich_byt_set_writeable;
 		}
 		break;
 
···
 			res->start = spi_base + SPIBASE_LPT;
 			res->end = res->start + SPIBASE_LPT_SZ - 1;
 
-			pci_read_config_dword(dev, BCR, &bcr);
-			info->writeable = !!(bcr & BCR_WPD);
+			info->set_writeable = lpc_ich_lpt_set_writeable;
+			info->data = dev;
 		}
 		break;
 
···
 			res->start = spi_base & 0xfffffff0;
 			res->end = res->start + SPIBASE_APL_SZ - 1;
 
-			pci_bus_read_config_dword(bus, spi, BCR, &bcr);
-			info->writeable = !!(bcr & BCR_WPD);
+			info->set_writeable = lpc_ich_bxt_set_writeable;
+			info->data = bus;
 		}
 
 		pci_bus_write_config_byte(bus, p2sb, 0xe1, 0x1);

drivers/mtd/spi-nor/controllers/intel-spi-pci.c

···
 #define BCR		0xdc
 #define BCR_WPD		BIT(0)
 
+static bool intel_spi_pci_set_writeable(void __iomem *base, void *data)
+{
+	struct pci_dev *pdev = data;
+	u32 bcr;
+
+	/* Try to make the chip read/write */
+	pci_read_config_dword(pdev, BCR, &bcr);
+	if (!(bcr & BCR_WPD)) {
+		bcr |= BCR_WPD;
+		pci_write_config_dword(pdev, BCR, bcr);
+		pci_read_config_dword(pdev, BCR, &bcr);
+	}
+
+	return bcr & BCR_WPD;
+}
+
 static const struct intel_spi_boardinfo bxt_info = {
 	.type = INTEL_SPI_BXT,
+	.set_writeable = intel_spi_pci_set_writeable,
 };
 
 static const struct intel_spi_boardinfo cnl_info = {
 	.type = INTEL_SPI_CNL,
+	.set_writeable = intel_spi_pci_set_writeable,
 };
 
 static int intel_spi_pci_probe(struct pci_dev *pdev,
···
 {
 	struct intel_spi_boardinfo *info;
 	struct intel_spi *ispi;
-	u32 bcr;
 	int ret;
 
 	ret = pcim_enable_device(pdev);
···
 	if (!info)
 		return -ENOMEM;
 
-	/* Try to make the chip read/write */
-	pci_read_config_dword(pdev, BCR, &bcr);
-	if (!(bcr & BCR_WPD)) {
-		bcr |= BCR_WPD;
-		pci_write_config_dword(pdev, BCR, bcr);
-		pci_read_config_dword(pdev, BCR, &bcr);
-	}
-	info->writeable = !!(bcr & BCR_WPD);
-
+	info->data = pdev;
 	ispi = intel_spi_probe(&pdev->dev, &pdev->resource[0], info);
 	if (IS_ERR(ispi))
 		return PTR_ERR(ispi);

drivers/mtd/spi-nor/controllers/intel-spi.c

···
  * @sregs: Start of software sequencer registers
  * @nregions: Maximum number of regions
  * @pr_num: Maximum number of protected range registers
- * @writeable: Is the chip writeable
  * @locked: Is SPI setting locked
  * @swseq_reg: Use SW sequencer in register reads/writes
  * @swseq_erase: Use SW sequencer in erase operation
···
 	void __iomem *sregs;
 	size_t nregions;
 	size_t pr_num;
-	bool writeable;
 	bool locked;
 	bool swseq_reg;
 	bool swseq_erase;
···
 				  INTEL_SPI_TIMEOUT * 1000);
 }
 
+static bool intel_spi_set_writeable(struct intel_spi *ispi)
+{
+	if (!ispi->info->set_writeable)
+		return false;
+
+	return ispi->info->set_writeable(ispi->base, ispi->info->data);
+}
+
 static int intel_spi_init(struct intel_spi *ispi)
 {
 	u32 opmenu0, opmenu1, lvscc, uvscc, val;
···
 		ispi->nregions = BYT_FREG_NUM;
 		ispi->pr_num = BYT_PR_NUM;
 		ispi->swseq_reg = true;
-
-		if (writeable) {
-			/* Disable write protection */
-			val = readl(ispi->base + BYT_BCR);
-			if (!(val & BYT_BCR_WPD)) {
-				val |= BYT_BCR_WPD;
-				writel(val, ispi->base + BYT_BCR);
-				val = readl(ispi->base + BYT_BCR);
-			}
-
-			ispi->writeable = !!(val & BYT_BCR_WPD);
-		}
-
 		break;
 
 	case INTEL_SPI_LPT:
···
 
 	default:
 		return -EINVAL;
+	}
+
+	/* Try to disable write protection if user asked to do so */
+	if (writeable && !intel_spi_set_writeable(ispi)) {
+		dev_warn(ispi->dev, "can't disable chip write protection\n");
+		writeable = false;
 	}
 
 	/* Disable #SMI generation from HW sequencer */
···
 		/*
 		 * If any of the regions have protection bits set, make the
 		 * whole partition read-only to be on the safe side.
+		 *
+		 * Also if the user did not ask the chip to be writeable
+		 * mask the bit too.
 		 */
-		if (intel_spi_is_protected(ispi, base, limit))
-			ispi->writeable = false;
+		if (!writeable || intel_spi_is_protected(ispi, base, limit))
+			part->mask_flags |= MTD_WRITEABLE;
 
 		end = (limit << 12) + 4096;
 		if (end > part->size)
···
 
 	ispi->dev = dev;
 	ispi->info = info;
-	ispi->writeable = info->writeable;
 
 	ret = intel_spi_init(ispi);
 	if (ret)
···
 	}
 
 	intel_spi_fill_partition(ispi, &part);
-
-	/* Prevent writes if not explicitly enabled */
-	if (!ispi->writeable || !writeable)
-		ispi->nor.mtd.flags &= ~MTD_WRITEABLE;
 
 	ret = mtd_device_register(&ispi->nor.mtd, &part, 1);
 	if (ret)

include/linux/platform_data/x86/intel-spi.h

···
 /**
  * struct intel_spi_boardinfo - Board specific data for Intel SPI driver
  * @type: Type which this controller is compatible with
- * @writeable: The chip is writeable
+ * @set_writeable: Try to make the chip writeable (optional)
+ * @data: Data to be passed to @set_writeable can be %NULL
  */
 struct intel_spi_boardinfo {
 	enum intel_spi_type type;
-	bool writeable;
+	bool (*set_writeable)(void __iomem *base, void *data);
+	void *data;
 };
 
 #endif /* INTEL_SPI_PDATA_H */