mtd: spi-nor: Add support for flag status register on Micron chips

Some new Micron SPI N25Q512 chips require reading the flag
status register to determine when operations have completed.

Signed-off-by: Chunhe Lan <Chunhe.Lan@freescale.com>
Change-Id: I52a87e1ae55da75248108d6db39f027318bacf22
Reviewed-on: http://git.am.freescale.net:8181/22632
Tested-by: Review Code-CDREVIEW <CDREVIEW@freescale.com>
Reviewed-by: Mingkai Hu <Mingkai.Hu@freescale.com>
Reviewed-by: Richard Schmitt <richard.schmitt@freescale.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 5df9d0d..dc15574 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -48,6 +48,25 @@ static int read_sr(struct spi_nor *nor)
 }
 
 /*
+ * Read the flag status register, returning its value in the location
+ * Return the status register value.
+ * Returns negative if error occurred.
+ */
+static int read_fsr(struct spi_nor *nor)
+{
+	int ret;
+	u8 val;
+
+	ret = nor->read_reg(nor, SPINOR_OP_RDFSR, &val, 1);
+	if (ret < 0) {
+		pr_err("error %d reading FSR\n", ret);
+		return ret;
+	}
+
+	return val;
+}
+
+/*
  * Read configuration register, returning its value in the
  * location. Return the configuration register value.
  * Returns negative if error occured.
@@ -178,6 +197,32 @@ static int spi_nor_wait_till_ready(struct spi_nor *nor)
 	return -ETIMEDOUT;
 }
 
+static int spi_nor_wait_till_fsr_ready(struct spi_nor *nor)
+{
+	unsigned long deadline;
+	int sr;
+	int fsr;
+
+	deadline = jiffies + MAX_READY_WAIT_JIFFIES;
+
+	do {
+		cond_resched();
+
+		sr = read_sr(nor);
+		if (sr < 0) {
+			break;
+		} else if (!(sr & SR_WIP)) {
+			fsr = read_fsr(nor);
+			if (fsr < 0)
+				break;
+			if (fsr & FSR_READY)
+				return 0;
+		}
+	} while (!time_after_eq(jiffies, deadline));
+
+	return -ETIMEDOUT;
+}
+
 /*
  * Service routine to read status register until ready, or timeout occurs.
  * Returns non-zero if error.
@@ -416,6 +461,7 @@ struct flash_info {
 #define	SPI_NOR_DUAL_READ	0x20    /* Flash supports Dual Read */
 #define	SPI_NOR_QUAD_READ	0x40    /* Flash supports Quad Read */
 #define	SPI_NOR_DDR_QUAD_READ	0x80    /* Flash supports DDR Quad Read */
+#define	USE_FSR			0x100	/* use flag status register */
 };
 
 #define INFO(_jedec_id, _ext_id, _sector_size, _n_sectors, _flags)	\
@@ -502,6 +548,7 @@ const struct spi_device_id spi_nor_ids[] = {
 	{ "n25q128a13",  INFO(0x20ba18, 0, 64 * 1024,  256, 0) },
 	{ "n25q256a",    INFO(0x20ba19, 0, 64 * 1024,  512, SECT_4K) },
 	{ "n25q512a",    INFO(0x20bb20, 0, 64 * 1024, 1024, SECT_4K) },
+	{ "n25q512ax3",	 INFO(0x20ba20, 0, 64 * 1024, 1024, USE_FSR) },
 
 	/* PMC */
 	{ "pm25lv512",   INFO(0,        0, 32 * 1024,    2, SECT_4K_PMC) },
@@ -1021,6 +1068,10 @@ int spi_nor_scan(struct spi_nor *nor, const struct spi_device_id *id,
 	else
 		mtd->_write = spi_nor_write;
 
+	if ((info->flags & USE_FSR) &&
+	    nor->wait_till_ready == spi_nor_wait_till_ready)
+		nor->wait_till_ready = spi_nor_wait_till_fsr_ready;
+
 	/* prefer "small sector" erase if possible */
 	if (info->flags & SECT_4K) {
 		nor->erase_opcode = SPINOR_OP_BE_4K;