[PATCH v2 1/2] mtd: spi-nor: Add SPI NOR layer PM support

[Zhiqiang Hou]

From: Hou Zhiqiang <Zhiqiang.Hou at freescale.com>

Add the Power Management API in SPI NOR framework.
The Power Management system will turn off power supply to SPI flash
when system suspending, and then the SPI flash will be in the reset
state after system resuming. As a result, the status&configurations
of SPI flash driver will mismatch with its current hardware state.
So reinitialize SPI flash to make sure it is resumed to the correct
state.
And the SPI NOR layer just do common configuration depending on the
records in structure spi_nor.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou at freescale.com>
---
V2:
 - New patch

 drivers/mtd/spi-nor/spi-nor.c | 44 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/mtd/spi-nor.h   |  9 +++++++++
 2 files changed, 53 insertions(+)

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 4988390..4030d37c 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -1365,6 +1365,50 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 }
 EXPORT_SYMBOL_GPL(spi_nor_scan);
 
+#ifdef CONFIG_PM_SLEEP
+static int spi_nor_hw_reinit(struct spi_nor *nor)
+{
+	const struct flash_info *info = NULL;
+	struct device *dev = nor->dev;
+	int ret;
+
+	info = spi_nor_read_id(nor);
+	if (JEDEC_MFR(info) == SNOR_MFR_ATMEL ||
+	    JEDEC_MFR(info) == SNOR_MFR_INTEL ||
+	    JEDEC_MFR(info) == SNOR_MFR_SST ||
+	    JEDEC_MFR(info) == SNOR_MFR_WINBOND) {
+		write_enable(nor);
+		write_sr(nor, 0);
+	}
+
+	if (nor->flash_read == SPI_NOR_QUAD) {
+		ret = set_quad_mode(nor, info);
+		if (ret) {
+			dev_err(dev, "quad mode not supported\n");
+			return ret;
+		}
+	}
+
+	if (nor->addr_width == 4 && !info->addr_width &&
+			JEDEC_MFR(info) != SNOR_MFR_SPANSION)
+		set_4byte(nor, info, 1);
+
+	return 0;
+}
+
+int spi_nor_suspend(struct spi_nor *nor)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(spi_nor_suspend);
+
+int spi_nor_resume(struct spi_nor *nor)
+{
+	return spi_nor_hw_reinit(nor);
+}
+EXPORT_SYMBOL_GPL(spi_nor_resume);
+#endif /* CONFIG_PM_SLEEP */
+
 static const struct flash_info *spi_nor_match_id(const char *name)
 {
 	const struct flash_info *id = spi_nor_ids;
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index c8723b6..d3a7888 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -201,4 +201,13 @@ struct spi_nor {
  */
 int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode);
 
+/**
+ * spi_nor_suspend/resume() - the SPI NOR layer PM API
+ * @nor:	the spi_nor structure
+ *
+ * Return: 0 for success, others for failure.
+ */
+int spi_nor_suspend(struct spi_nor *nor);
+int spi_nor_resume(struct spi_nor *nor);
+
 #endif
-- 
2.1.0.27.g96db324