[PATCH v3 04/13] mtd: st_spi_fsm: Fetch boot device locations from DT match tables

On Mon, 12 Jan 2015, Brian Norris wrote:

+ devicetree

On Mon, Dec 15, 2014 at 11:59:11AM +0000, Lee Jones wrote:

quoted

To trim down on the amount of properties used by this driver and to conform
to the newly agreed method of acquiring syscfg registers/offsets, we now
obtain this information using match tables.

In the process we are deprecating the old generic compatible string and
providing 3 shiny new ones for each of the support platforms.  The
deprecated compatible string will be removed in due course.

I'm not sure how this agreement was done, but by default, we expect not
to break backwards compatibility. This patch does just that.

quoted

Signed-off-by: Lee Jones <redacted>
---
 drivers/mtd/devices/st_spi_fsm.c | 75 ++++++++++++++++++++++++++++++----------
 1 file changed, 57 insertions(+), 18 deletions(-)

diff --git a/drivers/mtd/devices/st_spi_fsm.c b/drivers/mtd/devices/st_spi_fsm.c
index fac0fe9..d82394a 100644
--- a/drivers/mtd/devices/st_spi_fsm.c
+++ b/drivers/mtd/devices/st_spi_fsm.c

@@ -29,6 +29,21 @@
 #include "serial_flash_cmds.h"
 
 /*
+ * FSM SPI Boot Mode Registers/Masks
+ */
+#define STID127_SYSCON_BOOT_DEV_REG	0x0D8
+#define STID127_SYSCON_BOOT_DEV_SPI	0x068
+#define STID127_SYSCON_BOOT_DEV_MASK	0x07C
+
+#define STIH407_SYSCON_BOOT_DEV_REG	0x8C4
+#define STIH407_SYSCON_BOOT_DEV_SPI	0x068
+#define STIH407_SYSCON_BOOT_DEV_MASK	0x07C
+
+#define STIH416_SYSCON_BOOT_DEV_REG	0x958
+#define STIH416_SYSCON_BOOT_DEV_SPI	0x01A
+#define STIH416_SYSCON_BOOT_DEV_MASK	0x01F
+
+/*
  * FSM SPI Controller Registers
  */
 #define SPI_CLOCKDIV			0x0010

@@ -288,6 +303,12 @@ struct seq_rw_config {
 	uint8_t         dummy_cycles;   /* No. of DUMMY cycles */
 };
 
+struct stfsm_boot_dev {
+	uint32_t		reg;
+	uint32_t		spi;
+	uint32_t		mask;
+};
+
 /* SPI Flash Device Table */
 struct flash_info {
 	char            *name;

@@ -313,6 +334,24 @@ struct flash_info {
 	int             (*config)(struct stfsm *);
 };
 
+static struct stfsm_boot_dev stfsm_stid127_data = {
+	.reg  = STID127_SYSCON_BOOT_DEV_REG,
+	.spi  = STID127_SYSCON_BOOT_DEV_SPI,
+	.mask = STID127_SYSCON_BOOT_DEV_MASK,
+};
+
+static struct stfsm_boot_dev stfsm_stih407_data = {
+	.reg  = STIH407_SYSCON_BOOT_DEV_REG,
+	.spi  = STIH407_SYSCON_BOOT_DEV_SPI,
+	.mask = STIH407_SYSCON_BOOT_DEV_MASK,
+};
+
+static struct stfsm_boot_dev stfsm_stih416_data = {
+	.reg  = STIH416_SYSCON_BOOT_DEV_REG,
+	.spi  = STIH416_SYSCON_BOOT_DEV_SPI,
+	.mask = STIH416_SYSCON_BOOT_DEV_MASK,
+};
+
 static int stfsm_n25q_config(struct stfsm *fsm);
 static int stfsm_mx25_config(struct stfsm *fsm);
 static int stfsm_s25fl_config(struct stfsm *fsm);

@@ -1977,14 +2016,23 @@ static int stfsm_init(struct stfsm *fsm)
 	return 0;
 }
 
+static const struct of_device_id stfsm_match[] = {
+	{ .compatible = "st,spi-fsm" }, /* DEPRECATED */
+	{ .compatible = "st,stid127-spi-fsm", .data = &stfsm_stid127_data },
+	{ .compatible = "st,stih407-spi-fsm", .data = &stfsm_stih407_data },
+	{ .compatible = "st,stih416-spi-fsm", .data = &stfsm_stih416_data },
+	{},
+};
+MODULE_DEVICE_TABLE(of, stfsm_match);
+
 static void stfsm_fetch_platform_configs(struct platform_device *pdev)
 {
 	struct stfsm *fsm = platform_get_drvdata(pdev);
 	struct device_node *np = pdev->dev.of_node;
+	const struct stfsm_boot_dev *boot_dev;
+	const struct of_device_id *match;
 	struct regmap *regmap;
-	uint32_t boot_device_reg;
-	uint32_t boot_device_spi;
-	uint32_t boot_device;     /* Value we read from *boot_device_reg */
+	uint32_t boot_device;    /* Value we read from the boot dev mode pins */
 	int ret;
 
 	/* Booting from SPI NOR Flash is the default */

@@ -1998,21 +2046,18 @@ static void stfsm_fetch_platform_configs(struct platform_device *pdev)
 
 	fsm->reset_por = of_property_read_bool(np, "st,reset-por");
 
-	/* Where in the syscon the boot device information lives */
-	ret = of_property_read_u32(np, "st,boot-device-reg", &boot_device_reg);
-	if (ret)
+	match = of_match_node(stfsm_match, np);
+	if (!match)
 		goto boot_device_fail;
+	boot_dev = match->data;
 
-	/* Boot device value when booted from SPI NOR */
-	ret = of_property_read_u32(np, "st,boot-device-spi", &boot_device_spi);
+	ret = regmap_read(regmap, boot_dev->reg, &boot_device);

^^^ NULL pointer dereference for any existing DTB that uses the
"st,spi-fsm" compatible string. So I'll NAK this patch as-is. Either we
need to completely drop the "deprecated" compatible property (what's the
point binding to it, if we're going to OOPS on it anyway), or else we
need to maintain both methods (at least for whatever deprecation period
is deemed acceptable).

Great spot Brian.

So, as I explained in reply to the cover-letter, this driver isn't
being used in anger yet.  As the driver is still considered
in-progress I take the view that it's perfectly okay to remove the old
compatible string and not match on it at all.

I'll make the necessary changes and re-submit.

quoted

 	if (ret)
 		goto boot_device_fail;
 
-	ret = regmap_read(regmap, boot_device_reg, &boot_device);
-	if (ret)
-		goto boot_device_fail;
+	boot_device &= boot_dev->mask;
 
-	if (boot_device != boot_device_spi)
+	if (boot_device != boot_dev->spi)
 		fsm->booted_from_spi = false;
 
 	return;

@@ -2156,12 +2201,6 @@ static int stfsmfsm_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(stfsm_pm_ops, stfsmfsm_suspend, stfsmfsm_resume);
 
-static const struct of_device_id stfsm_match[] = {
-	{ .compatible = "st,spi-fsm", },
-	{},
-};
-MODULE_DEVICE_TABLE(of, stfsm_match);
-
 static struct platform_driver stfsm_driver = {
 	.probe		= stfsm_probe,
 	.remove		= stfsm_remove,

Brian

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org ? Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog