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 <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mauro Lima <mauro.lima@eclypsium.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220209122706.42439-2-mika.westerberg@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 54 insertions, 5 deletions

diff --git a/drivers/mfd/lpc_ich.c b/drivers/mfd/lpc_ich.c
index f10e53187f67..9ffab9aafd81 100644
--- a/drivers/mfd/lpc_ich.c
+++ b/drivers/mfd/lpc_ich.c
@@ -63,6 +63,8 @@
 #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
@@ -1084,12 +1086,57 @@ wdt_done:
 	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)
@@ -1103,6 +1150,8 @@ static int lpc_ich_init_spi(struct pci_dev *dev)
 		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;
 
@@ -1113,8 +1162,8 @@ static int lpc_ich_init_spi(struct pci_dev *dev)
 			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;
 
@@ -1135,8 +1184,8 @@ static int lpc_ich_init_spi(struct pci_dev *dev)
 			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);