sf: Add a method to obtain the block-protect setting

It is useful to obtain the block-protect setting of the SPI flash, so we
know whether it is fully open or (perhaps partially) write-protected. Add
a method for this. Update the sandbox driver to process this operation and
add a test.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/sandbox/include/asm/test.h

@@ -113,4 +113,12 @@ int sandbox_osd_get_mem(struct udevice *dev, u8 *buf, size_t buflen);
 int sandbox_pwm_get_config(struct udevice *dev, uint channel, uint *period_nsp,
 			   uint *duty_nsp, bool *enablep, bool *polarityp);
 
+/**
+ * sandbox_sf_set_block_protect() - Set the BP bits of the status register
+ *
+ * @dev: Device to update
+ * @bp_mask: BP bits to set (bits 2:0, so a value of 0 to 7)
+ */
+void sandbox_sf_set_block_protect(struct udevice *dev, int bp_mask);
+
 #endif

drivers/mtd/spi/sandbox.c

@@ -57,6 +57,8 @@ static const char *sandbox_sf_state_name(enum sandbox_sf_state state)
 /* Bits for the status register */
 #define STAT_WIP	(1 << 0)
 #define STAT_WEL	(1 << 1)
+#define STAT_BP_SHIFT	2
+#define STAT_BP_MASK	(7 << STAT_BP_SHIFT)
 
 /* Assume all SPI flashes have 3 byte addresses since they do atm */
 #define SF_ADDR_LEN	3
@@ -102,6 +104,14 @@ struct sandbox_spi_flash_plat_data {
 	int cs;
 };
 
+void sandbox_sf_set_block_protect(struct udevice *dev, int bp_mask)
+{
+	struct sandbox_spi_flash *sbsf = dev_get_priv(dev);
+
+	sbsf->status &= ~STAT_BP_MASK;
+	sbsf->status |= bp_mask << STAT_BP_SHIFT;
+}
+
 /**
  * This is a very strange probe function. If it has platform data (which may
  * have come from the device tree) then this function gets the filename and

drivers/mtd/spi/sf-uclass.c

@@ -28,6 +28,15 @@ int spi_flash_erase_dm(struct udevice *dev, u32 offset, size_t len)
 	return log_ret(sf_get_ops(dev)->erase(dev, offset, len));
 }
 
+int spl_flash_get_sw_write_prot(struct udevice *dev)
+{
+	struct dm_spi_flash_ops *ops = sf_get_ops(dev);
+
+	if (!ops->get_sw_write_prot)
+		return -ENOSYS;
+	return log_ret(ops->get_sw_write_prot(dev));
+}
+
 /*
  * TODO(sjg@chromium.org): This is an old-style function. We should remove
  * it when all SPI flash drivers use dm

drivers/mtd/spi/sf_internal.h

@@ -170,6 +170,9 @@ int spi_flash_cmd_write(struct spi_slave *spi, const u8 *cmd, size_t cmd_len,
 /* Flash erase(sectors) operation, support all possible erase commands */
 int spi_flash_cmd_erase_ops(struct spi_flash *flash, u32 offset, size_t len);
 
+/* Get software write-protect value (BP bits) */
+int spi_flash_cmd_get_sw_write_prot(struct spi_flash *flash);
+
 /* Lock stmicro spi flash region */
 int stm_lock(struct spi_flash *flash, u32 ofs, size_t len);
 

drivers/mtd/spi/sf_probe.c

@@ -124,6 +124,13 @@ static int spi_flash_std_erase(struct udevice *dev, u32 offset, size_t len)
 	return spi_flash_cmd_erase_ops(flash, offset, len);
 }
 
+static int spi_flash_std_get_sw_write_prot(struct udevice *dev)
+{
+	struct spi_flash *flash = dev_get_uclass_priv(dev);
+
+	return spi_flash_cmd_get_sw_write_prot(flash);
+}
+
 static int spi_flash_std_probe(struct udevice *dev)
 {
 	struct spi_slave *slave = dev_get_parent_priv(dev);
@@ -141,6 +148,7 @@ static const struct dm_spi_flash_ops spi_flash_std_ops = {
 	.read = spi_flash_std_read,
 	.write = spi_flash_std_write,
 	.erase = spi_flash_std_erase,
+	.get_sw_write_prot = spi_flash_std_get_sw_write_prot,
 };
 
 static const struct udevice_id spi_flash_std_ids[] = {

drivers/mtd/spi/spi_flash.c

@@ -110,6 +110,18 @@ static int write_cr(struct spi_flash *flash, u8 wc)
 }
 #endif
 
+int spi_flash_cmd_get_sw_write_prot(struct spi_flash *flash)
+{
+	u8 status;
+	int ret;
+
+	ret = read_sr(flash, &status);
+	if (ret)
+		return ret;
+
+	return (status >> 2) & 7;
+}
+
 #ifdef CONFIG_SPI_FLASH_BAR
 /*
  * This "clean_bar" is necessary in a situation when one was accessing

include/spi_flash.h

@@ -112,6 +112,19 @@ struct dm_spi_flash_ops {
 	int (*write)(struct udevice *dev, u32 offset, size_t len,
 		     const void *buf);
 	int (*erase)(struct udevice *dev, u32 offset, size_t len);
+	/**
+	 * get_sw_write_prot() - Check state of software write-protect feature
+	 *
+	 * SPI flash chips can lock a region of the flash defined by a
+	 * 'protected area'. This function checks if this protected area is
+	 * defined.
+	 *
+	 * @dev:	SPI flash device
+	 * @return 0 if no region is write-protected, 1 if a region is
+	 *	write-protected, -ENOSYS if the driver does not implement this,
+	 *	other -ve value on error
+	 */
+	int (*get_sw_write_prot)(struct udevice *dev);
 };
 
 /* Access the serial operations for a device */
@@ -153,6 +166,20 @@ int spi_flash_write_dm(struct udevice *dev, u32 offset, size_t len,
  */
 int spi_flash_erase_dm(struct udevice *dev, u32 offset, size_t len);
 
+/**
+ * spl_flash_get_sw_write_prot() - Check state of software write-protect feature
+ *
+ * SPI flash chips can lock a region of the flash defined by a
+ * 'protected area'. This function checks if this protected area is
+ * defined.
+ *
+ * @dev:	SPI flash device
+ * @return 0 if no region is write-protected, 1 if a region is
+ *	write-protected, -ENOSYS if the driver does not implement this,
+ *	other -ve value on error
+ */
+int spl_flash_get_sw_write_prot(struct udevice *dev);
+
 int spi_flash_probe_bus_cs(unsigned int busnum, unsigned int cs,
 			   unsigned int max_hz, unsigned int spi_mode,
 			   struct udevice **devp);

test/dm/sf.c

@@ -11,6 +11,7 @@
 #include <spi.h>
 #include <spi_flash.h>
 #include <asm/state.h>
+#include <asm/test.h>
 #include <dm/test.h>
 #include <dm/util.h>
 #include <test/ut.h>
@@ -45,6 +46,14 @@ static int dm_test_spi_flash(struct unit_test_state *uts)
 	ut_assertok(spi_flash_read_dm(dev, 0, size, dst));
 	ut_assertok(memcmp(src, dst, size));
 
+	/* Try the write-protect stuff */
+	ut_assertok(uclass_first_device_err(UCLASS_SPI_EMUL, &emul));
+	ut_asserteq(0, spl_flash_get_sw_write_prot(dev));
+	sandbox_sf_set_block_protect(emul, 1);
+	ut_asserteq(1, spl_flash_get_sw_write_prot(dev));
+	sandbox_sf_set_block_protect(emul, 0);
+	ut_asserteq(0, spl_flash_get_sw_write_prot(dev));
+
 	/*
 	 * Since we are about to destroy all devices, we must tell sandbox
 	 * to forget the emulation device