[PATCH v3 28/36] mtd: st_spi_fsm: Supply a busy wait for post-write status

Lee Jones
2013-11-29T12:22:41Z

When we write data to the Serial Flash chip we'll wait a predetermined
period of time before giving up. During that period of time we poll the
status register until completion.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
drivers/mtd/devices/st_spi_fsm.c | 52 ++++++++++++++++++++++++++++++++++++++++
drivers/mtd/devices/st_spi_fsm.h | 10 ++++++++
2 files changed, 62 insertions(+)

diff --git a/drivers/mtd/devices/st_spi_fsm.c b/drivers/mtd/devices/st_spi_fsm.c
index c08805f..d8fc97b 100644
--- a/drivers/mtd/devices/st_spi_fsm.c
+++ b/drivers/mtd/devices/st_spi_fsm.c
@@ -118,6 +118,22 @@ static struct stfsm_seq stfsm_seq_read_jedec = {
SEQ_CFG_STARTSEQ),
};

+static struct stfsm_seq stfsm_seq_read_status_fifo = {
+ .data_size = TRANSFER_SIZE(4),
+ .seq_opc[0] = (SEQ_OPC_PADS_1 |
+ SEQ_OPC_CYCLES(8) |
+ SEQ_OPC_OPCODE(FLASH_CMD_RDSR)),
+ .seq = {
+ STFSM_INST_CMD1,
+ STFSM_INST_DATA_READ,
+ STFSM_INST_STOP,
+ },
+ .seq_cfg = (SEQ_CFG_PADS_1 |
+ SEQ_CFG_READNOTWRITE |
+ SEQ_CFG_CSDEASSERT |
+ SEQ_CFG_STARTSEQ),
+};
+
static struct stfsm_seq stfsm_seq_erase_sector = {
/* 'addr_cfg' configured during initialisation */
.seq_opc = {
@@ -292,6 +308,42 @@ static int stfsm_enter_32bit_addr(struct stfsm *fsm, int enter)
return 0;
}

+static uint8_t stfsm_wait_busy(struct stfsm *fsm)
+{
+ struct stfsm_seq *seq = &stfsm_seq_read_status_fifo;
+ unsigned long deadline;
+ uint32_t status;
+
+ /* Use RDRS1 */
+ seq->seq_opc[0] = (SEQ_OPC_PADS_1 |
+ SEQ_OPC_CYCLES(8) |
+ SEQ_OPC_OPCODE(FLASH_CMD_RDSR));
+
+ /* Load read_status sequence */
+ stfsm_load_seq(fsm, seq);
+
+ /* Repeat until busy bit is deasserted, or timeout */
+ deadline = jiffies + FLASH_MAX_BUSY_WAIT;
+ do {
+ cond_resched();
+
+ stfsm_wait_seq(fsm);
+
+ stfsm_read_fifo(fsm, &status, 4);
+
+ if ((status & FLASH_STATUS_BUSY) == 0)
+ return 0;
+
+ /* Restart */
+ writel(seq->seq_cfg, fsm->base + SPI_FAST_SEQ_CFG);
+
+ } while (!time_after_eq(jiffies, deadline));
+
+ dev_err(fsm->dev, "timeout on wait_busy\n");
+
+ return -EIO;
+}
+
static int stfsm_wrvcr(struct stfsm *fsm, uint8_t data)
{
struct stfsm_seq *seq = &stfsm_seq_wrvcr;
diff --git a/drivers/mtd/devices/st_spi_fsm.h b/drivers/mtd/devices/st_spi_fsm.h
index e168296..5143843 100644
--- a/drivers/mtd/devices/st_spi_fsm.h
+++ b/drivers/mtd/devices/st_spi_fsm.h
@@ -229,8 +229,18 @@
#define FLASH_CMD_READ4_1_1_4 0x6c
#define FLASH_CMD_READ4_1_4_4 0xec

+/* Status register */
+#define FLASH_STATUS_BUSY 0x01
+#define FLASH_STATUS_WEL 0x02
+#define FLASH_STATUS_BP0 0x04
+#define FLASH_STATUS_BP1 0x08
+#define FLASH_STATUS_BP2 0x10
+#define FLASH_STATUS_SRWP0 0x80
+#define FLASH_STATUS_TIMEOUT 0xff
+
#define FLASH_PAGESIZE 256 /* In Bytes */
#define FLASH_PAGESIZE_32 FLASH_PAGESIZE / 4 /* In uint32_t */
+#define FLASH_MAX_BUSY_WAIT (300 * HZ) /* Maximum 'CHIPERASE' time */

/*
* Flags to tweak operation of default read/write/erase routines
--
1.8.3.2