linux-kernel - [PATCH 07/10] mtd: st_spi_fsm: Add support for JEDEC ID extraction

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Message-Id: <1384438956-31153-8-git-send-email-lee.jones@linaro.org>
Date:	Thu, 14 Nov 2013 14:22:33 +0000
From:	Lee Jones <lee.jones@...aro.org>
To:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:	linus.walleij@...aro.org, dwmw2@...radead.org,
	linux-mtd@...ts.infradead.org, angus.clark@...com,
	Lee Jones <lee.jones@...aro.org>
Subject: [PATCH 07/10] 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.

Signed-off-by: Lee Jones <lee.jones@...aro.org>
---
 drivers/mtd/devices/st_spi_fsm.c | 63 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/drivers/mtd/devices/st_spi_fsm.c b/drivers/mtd/devices/st_spi_fsm.c
index 6691eaf..2899e0f 100644
--- a/drivers/mtd/devices/st_spi_fsm.c
+++ b/drivers/mtd/devices/st_spi_fsm.c
@@ -92,6 +92,22 @@ struct stfsm_seq {
 } __attribute__((__packed__, aligned(4)));
 #define STFSM_SEQ_SIZE sizeof(struct stfsm_seq)
 
+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;
@@ -158,6 +174,50 @@ static void stfsm_read_fifo(struct stfsm *fsm, uint32_t *buf,
 	}
 }
 
+static int 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);
+
+	return 0;
+}
+
+static struct flash_info * stfsm_jedec_probe(struct stfsm *fsm)
+{
+	u16                     ext_jedec;
+	u32			jedec;
+	u8			id[5];
+	int			ret;
+
+	/*
+	 * 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.
+	 */
+
+	ret = stfsm_read_jedec(fsm, id);
+	if (ret) {
+		dev_info(fsm->dev, "Error reading JEDEC ID\n");
+		return NULL;
+	}
+
+	jedec     = id[0] << 16 | id[1] << 8 | id[2];
+	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 void stfsm_clear_fifo(struct stfsm *fsm)
 {
 	uint32_t avail;
@@ -310,6 +370,9 @@ static int stfsm_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	/* Detect SPI FLASH device */
+	stfsm_jedec_probe(fsm);
+
 	platform_set_drvdata(pdev, fsm);
 
 	fsm->mtd.dev.parent   = &pdev->dev;
-- 
1.8.1.2

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