[PATCH v2, 1/1] mtd: devices: m25p80: Add PM suspend resume support

[Kamal Dasu]

Adding PM support so as to be able to probe spi-nor flash
on resume. There are vendor specific commands to setup
the transfer mode and enable read/write as part of
spi_nor_scan(), done on initial probe and needed on resume().
The spi-nor structure is private to the m25p driver and hence
is the only place this can be done without having to duplicate
code in controller driver.

Signed-off-by: Kamal Dasu <kdasu.kdev at gmail.com>
---
 drivers/mtd/devices/m25p80.c | 68 +++++++++++++++++++++++++++++++-------------
 1 file changed, 48 insertions(+), 20 deletions(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 9cf7fcd..48c3f64 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -186,6 +186,39 @@ static ssize_t m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
 }
 
 /*
+ * scan for spi nor flash vendor parts and setup
+ * read/write mode
+ */
+static int m25p_nor_flash_scan(struct device *dev)
+{
+	struct m25p *flash = dev_get_drvdata(dev);
+	struct flash_platform_data	*data;
+	char *flash_name = NULL;
+	enum read_mode mode = SPI_NOR_NORMAL;
+
+	data = dev_get_platdata(dev);
+
+	/* For some (historical?) reason many platforms provide two different
+	 * names in flash_platform_data: "name" and "type". Quite often name is
+	 * set to "m25p80" and then "type" provides a real chip name.
+	 * If that's the case, respect "type" and ignore a "name".
+	 */
+	if (data && data->type)
+		flash_name = data->type;
+	else if (!strcmp(flash->spi->modalias, "spi-nor"))
+		flash_name = NULL; /* auto-detect */
+	else
+		flash_name = flash->spi->modalias;
+
+	if (flash->spi->mode & SPI_RX_QUAD)
+		mode = SPI_NOR_QUAD;
+	else if (flash->spi->mode & SPI_RX_DUAL)
+		mode = SPI_NOR_DUAL;
+
+	return spi_nor_scan(&flash->spi_nor, flash_name, mode);
+}
+
+/*
  * board specific setup should have ensured the SPI clock used here
  * matches what the READ command supports, at least until this driver
  * understands FAST_READ (for clocks over 25 MHz).
@@ -195,8 +228,6 @@ static int m25p_probe(struct spi_device *spi)
 	struct flash_platform_data	*data;
 	struct m25p *flash;
 	struct spi_nor *nor;
-	enum read_mode mode = SPI_NOR_NORMAL;
-	char *flash_name;
 	int ret;
 
 	data = dev_get_platdata(&spi->dev);
@@ -220,27 +251,11 @@ static int m25p_probe(struct spi_device *spi)
 	spi_set_drvdata(spi, flash);
 	flash->spi = spi;
 
-	if (spi->mode & SPI_RX_QUAD)
-		mode = SPI_NOR_QUAD;
-	else if (spi->mode & SPI_RX_DUAL)
-		mode = SPI_NOR_DUAL;
-
 	if (data && data->name)
 		nor->mtd.name = data->name;
 
-	/* For some (historical?) reason many platforms provide two different
-	 * names in flash_platform_data: "name" and "type". Quite often name is
-	 * set to "m25p80" and then "type" provides a real chip name.
-	 * If that's the case, respect "type" and ignore a "name".
-	 */
-	if (data && data->type)
-		flash_name = data->type;
-	else if (!strcmp(spi->modalias, "spi-nor"))
-		flash_name = NULL; /* auto-detect */
-	else
-		flash_name = spi->modalias;
+	ret = m25p_nor_flash_scan(nor->dev);
 
-	ret = spi_nor_scan(nor, flash_name, mode);
 	if (ret)
 		return ret;
 
@@ -248,7 +263,6 @@ static int m25p_probe(struct spi_device *spi)
 				   data ? data->nr_parts : 0);
 }
 
-
 static int m25p_remove(struct spi_device *spi)
 {
 	struct m25p	*flash = spi_get_drvdata(spi);
@@ -319,10 +333,24 @@ static const struct of_device_id m25p_of_table[] = {
 };
 MODULE_DEVICE_TABLE(of, m25p_of_table);
 
+#ifdef CONFIG_PM_SLEEP
+static int m25p_suspend(struct device *dev)
+{
+	return 0;
+}
+
+static int m25p_resume(struct device *dev)
+{
+	return m25p_nor_flash_scan(dev);
+}
+#endif
+static SIMPLE_DEV_PM_OPS(m25p_pm_ops, m25p_suspend, m25p_resume);
+
 static struct spi_driver m25p80_driver = {
 	.driver = {
 		.name	= "m25p80",
 		.of_match_table = m25p_of_table,
+		.pm	= &m25p_pm_ops,
 	},
 	.id_table	= m25p_ids,
 	.probe	= m25p_probe,
-- 
1.9.1