mtd: st_spi_fsm: Add support for JEDEC ID extraction

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=1bd512b562dde92dae90036c4e6fd91f3870e44f
Commit:     1bd512b562dde92dae90036c4e6fd91f3870e44f
Parent:     030e82dc6386f23bcd05876b452d2618dd8046b4
Author:     Lee Jones <lee.jones at linaro.org>
AuthorDate: Thu Mar 20 09:20:38 2014 +0000
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Thu Mar 20 04:17:15 2014 -0700

    mtd: st_spi_fsm: Add support for JEDEC ID extraction
    
    Once we start supporting devices it will be handy go detect them
    dynamically. This will be done using the chip's unique JEDEC ID. This
    patch allows us to extract a device's JEDEC ID using the a predefined
    FSM register write sequence.
    
    Acked-by Angus Clark <angus.clark at st.com>
    Signed-off-by: Lee Jones <lee.jones at linaro.org>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
---
 drivers/mtd/devices/st_spi_fsm.c | 55 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/drivers/mtd/devices/st_spi_fsm.c b/drivers/mtd/devices/st_spi_fsm.c
index 73e0f27..9fc0b19 100644
--- a/drivers/mtd/devices/st_spi_fsm.c
+++ b/drivers/mtd/devices/st_spi_fsm.c
@@ -219,6 +219,22 @@ struct stfsm_seq {
 	uint32_t seq_cfg;
 } __packed __aligned(4);
 
+static struct stfsm_seq stfsm_seq_read_jedec = {
+	.data_size = TRANSFER_SIZE(8),
+	.seq_opc[0] = (SEQ_OPC_PADS_1 |
+		       SEQ_OPC_CYCLES(8) |
+		       SEQ_OPC_OPCODE(FLASH_CMD_RDID)),
+	.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 inline int stfsm_is_idle(struct stfsm *fsm)
 {
 	return readl(fsm->base + SPI_FAST_SEQ_STA) & 0x10;
@@ -307,6 +323,42 @@ static void stfsm_read_fifo(struct stfsm *fsm, uint32_t *buf,
 	}
 }
 
+static void stfsm_read_jedec(struct stfsm *fsm, uint8_t *const jedec)
+{
+	const struct stfsm_seq *seq = &stfsm_seq_read_jedec;
+	uint32_t tmp[2];
+
+	stfsm_load_seq(fsm, seq);
+
+	stfsm_read_fifo(fsm, tmp, 8);
+
+	memcpy(jedec, tmp, 5);
+
+	stfsm_wait_seq(fsm);
+}
+
+static struct flash_info *stfsm_jedec_probe(struct stfsm *fsm)
+{
+	u16                     ext_jedec;
+	u32			jedec;
+	u8			id[5];
+
+	stfsm_read_jedec(fsm, id);
+
+	jedec     = id[0] << 16 | id[1] << 8 | id[2];
+	/*
+	 * JEDEC also defines an optional "extended device information"
+	 * string for after vendor-specific data, after the three bytes
+	 * we use here. Supporting some chips might require using it.
+	 */
+	ext_jedec = id[3] << 8  | id[4];
+
+	dev_dbg(fsm->dev, "JEDEC =  0x%08x [%02x %02x %02x %02x %02x]\n",
+		jedec, id[0], id[1], id[2], id[3], id[4]);
+
+	return NULL;
+}
+
 static int stfsm_set_mode(struct stfsm *fsm, uint32_t mode)
 {
 	int ret, timeout = 10;
@@ -436,6 +488,9 @@ static int stfsm_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	/* Detect SPI FLASH device */
+	stfsm_jedec_probe(fsm);
+
 	fsm->mtd.dev.parent	= &pdev->dev;
 	fsm->mtd.type		= MTD_NORFLASH;
 	fsm->mtd.writesize	= 4;