[PATCH RFC 5/8] mtd: m25p80: add support of dual and quad spi protocols to all commands

Cyrille Pitchen
2016-04-13T17:25:18Z

Before this patch, m25p80_read() supported few SPI protocols:
- regular SPI 1-1-1
- SPI Dual Output 1-1-2
- SPI Quad Output 1-1-4
On the other hand, all other m25p80_*() hooks only supported SPI 1-1-1.

However once their Quad mode enabled, Micron and Macronix spi-nor memories
expect all commands to use the SPI 4-4-4 protocol.

Also, once their Dual mode enabled, Micron spi-nor memories expect all
commands to use the SPI-2-2-2 protocol.

So this patch adds support to all currently existing SPI protocols to
cover as many protocols as possible.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
---
drivers/mtd/devices/m25p80.c | 200 +++++++++++++++++++++++++++++++++----------
1 file changed, 155 insertions(+), 45 deletions(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 12112f7ae1a4..d4a3bc0e4c3f 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -27,22 +27,64 @@
#include <linux/spi/flash.h>
#include <linux/mtd/spi-nor.h>

-#define MAX_CMD_SIZE 6
+#define MAX_CMD_SIZE 16
struct m25p {
struct spi_device *spi;
struct spi_nor spi_nor;
u8 command[MAX_CMD_SIZE];
};

+static inline int m25p80_proto2nbits(enum spi_nor_protocol proto,
+ unsigned *code_nbits,
+ unsigned *addr_nbits,
+ unsigned *data_nbits)
+{
+ if (code_nbits)
+ *code_nbits = SNOR_PROTO_CODE_FROM_PROTO(proto);
+ if (addr_nbits)
+ *addr_nbits = SNOR_PROTO_ADDR_FROM_PROTO(proto);
+ if (data_nbits)
+ *data_nbits = SNOR_PROTO_DATA_FROM_PROTO(proto);
+
+ return 0;
+}
+
static int m25p80_read_reg(struct spi_nor *nor, u8 code, u8 *val, int len)
{
struct m25p *flash = nor->priv;
struct spi_device *spi = flash->spi;
+ unsigned code_nbits, data_nbits;
+ struct spi_transfer xfers[2];
int ret;

- ret = spi_write_then_read(spi, &code, 1, val, len);
+ /* Check the total length of command op code and data. */
+ if (len + 1 > MAX_CMD_SIZE)
+ return -EINVAL;
+
+ /* Get transfer protocols (addr_nbits is not relevant here). */
+ ret = m25p80_proto2nbits(nor->reg_proto,
+ &code_nbits, NULL, &data_nbits);
+ if (ret < 0)
+ return ret;
+
+ /* Set up transfers. */
+ memset(xfers, 0, sizeof(xfers));
+
+ flash->command[0] = code;
+ xfers[0].len = 1;
+ xfers[0].tx_buf = flash->command;
+ xfers[0].tx_nbits = code_nbits;
+
+ xfers[1].len = len;
+ xfers[1].rx_buf = &flash->command[1];
+ xfers[1].rx_nbits = data_nbits;
+
+ /* Process command. */
+ ret = spi_sync_transfer(spi, xfers, 2);
if (ret < 0)
dev_err(&spi->dev, "error %d reading %x\n", ret, code);
+ else
+ memcpy(val, &flash->command[1], len);

return ret;
}
@@ -65,12 +107,42 @@ static int m25p80_write_reg(struct spi_nor *nor, u8 opcode, u8 *buf, int len)
{
struct m25p *flash = nor->priv;
struct spi_device *spi = flash->spi;
+ unsigned code_nbits, data_nbits, num_xfers = 1;
+ struct spi_transfer xfers[2];
+ int ret;
+
+ /* Check the total length of command op code and data. */
+ if (buf && (len + 1 > MAX_CMD_SIZE))
+ return -EINVAL;
+
+ /* Get transfer protocols (addr_nbits is not relevant here). */
+ ret = m25p80_proto2nbits(nor->reg_proto,
+ &code_nbits, NULL, &data_nbits);
+ if (ret < 0)
+ return ret;
+
+ /* Set up transfer(s). */
+ memset(xfers, 0, sizeof(xfers));

flash->command[0] = opcode;
- if (buf)
+ xfers[0].len = 1;
+ xfers[0].tx_buf = flash->command;
+ xfers[0].tx_nbits = code_nbits;
+
+ if (buf) {
memcpy(&flash->command[1], buf, len);
+ if (data_nbits == code_nbits) {
+ xfers[0].len += len;
+ } else {
+ xfers[1].len = len;
+ xfers[1].tx_buf = &flash->command[1];
+ xfers[1].tx_nbits = data_nbits;
+ num_xfers++;
+ }
+ }

- return spi_write(spi, flash->command, len + 1);
+ /* Process command. */
+ return spi_sync_transfer(spi, xfers, num_xfers);
}

static void m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
@@ -78,43 +150,54 @@ static void m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
{
struct m25p *flash = nor->priv;
struct spi_device *spi = flash->spi;
- struct spi_transfer t[2] = {};
+ unsigned code_nbits, addr_nbits, data_nbits, num_xfers = 1;
+ struct spi_transfer xfers[3];
struct spi_message m;
- int cmd_sz = m25p_cmdsz(nor);
-
- spi_message_init(&m);
+ int ret, cmd_sz = m25p_cmdsz(nor);

if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
cmd_sz = 1;

- flash->command[0] = nor->program_opcode;
- m25p_addr2cmd(nor, to, flash->command);
+ /* Get transfer protocols. */
+ ret = m25p80_proto2nbits(nor->write_proto,
+ &code_nbits, &addr_nbits, &data_nbits);
+ if (ret < 0) {
+ *retlen = 0;
+ return;
+ }

- t[0].tx_buf = flash->command;
- t[0].len = cmd_sz;
- spi_message_add_tail(&t[0], &m);
+ /* Set up transfers. */
+ memset(xfers, 0, sizeof(xfers));
+
+ flash->command[0] = nor->program_opcode;
+ xfers[0].len = 1;
+ xfers[0].tx_buf = flash->command;
+ xfers[0].tx_nbits = code_nbits;
+
+ if (cmd_sz > 1) {
+ m25p_addr2cmd(nor, to, flash->command);
+ if (addr_nbits == code_nbits) {
+ xfers[0].len += nor->addr_width;
+ } else {
+ xfers[1].len = nor->addr_width;
+ xfers[1].tx_buf = &flash->command[1];
+ xfers[1].tx_nbits = addr_nbits;
+ num_xfers++;
+ }
+ }

- t[1].tx_buf = buf;
- t[1].len = len;
- spi_message_add_tail(&t[1], &m);
+ xfers[num_xfers].len = len;
+ xfers[num_xfers].tx_buf = buf;
+ xfers[num_xfers].tx_nbits = data_nbits;
+ num_xfers++;

+ /* Process command. */
+ spi_message_init_with_transfers(&m, xfers, num_xfers);
spi_sync(spi, &m);

*retlen += m.actual_length - cmd_sz;
}

-static inline unsigned int m25p80_rx_nbits(struct spi_nor *nor)
-{
- switch (SNOR_PROTO_DATA_FROM_PROTO(nor->read_proto)) {
- case 2:
- return 2;
- case 4:
- return 4;
- default:
- return 0;
- }
-}
-
/*
* Read an address range from the nor chip. The address range
* may be any size provided it is within the physical boundaries.
@@ -124,13 +207,24 @@ static int m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
{
struct m25p *flash = nor->priv;
struct spi_device *spi = flash->spi;
- struct spi_transfer t[2];
- struct spi_message m;
+ unsigned code_nbits, addr_nbits, data_nbits, num_xfers = 1;
unsigned int dummy = nor->read_dummy;
+ struct spi_transfer xfers[3];
+ struct spi_message m;
+ int ret;
+
+ /* Get transfer protocols. */
+ ret = m25p80_proto2nbits(nor->read_proto,
+ &code_nbits, &addr_nbits, &data_nbits);
+ if (ret < 0) {
+ *retlen = 0;
+ return ret;
+ }

/* convert the dummy cycles to the number of bytes */
- dummy /= 8;
+ dummy = (dummy * addr_nbits) / 8;

+ /* Use the SPI flash API if supported. */
if (spi_flash_read_supported(spi)) {
struct spi_flash_read_message msg;
int ret;
@@ -143,31 +237,47 @@ static int m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
msg.read_opcode = nor->read_opcode;
msg.addr_width = nor->addr_width;
msg.dummy_bytes = dummy;
- /* TODO: Support other combinations */
- msg.opcode_nbits = SPI_NBITS_SINGLE;
- msg.addr_nbits = SPI_NBITS_SINGLE;
- msg.data_nbits = m25p80_rx_nbits(nor);
+ msg.opcode_nbits = code_nbits;
+ msg.addr_nbits = addr_nbits;
+ msg.data_nbits = data_nbits;

ret = spi_flash_read(spi, &msg);
*retlen = msg.retlen;
return ret;
}

- spi_message_init(&m);
- memset(t, 0, (sizeof t));
+ /* Set up transfers. */
+ memset(xfers, 0, sizeof(xfers));

flash->command[0] = nor->read_opcode;
- m25p_addr2cmd(nor, from, flash->command);
+ xfers[0].len = 1;
+ xfers[0].tx_buf = flash->command;
+ xfers[0].tx_nbits = code_nbits;

- t[0].tx_buf = flash->command;
- t[0].len = m25p_cmdsz(nor) + dummy;
- spi_message_add_tail(&t[0], &m);
+ m25p_addr2cmd(nor, from, flash->command);
+ /*
+ * Clear all dummy/mode cycle bits to avoid sending some manufacturer
+ * specific pattern, which might make the memory enter its Continuous
+ * Read mode by mistake.
+ */
+ memset(flash->command + 1 + nor->addr_width, 0, dummy);
+
+ if (addr_nbits == code_nbits) {
+ xfers[0].len += nor->addr_width + dummy;
+ } else {
+ xfers[1].len = nor->addr_width + dummy;
+ xfers[1].tx_buf = &flash->command[1];
+ xfers[1].tx_nbits = addr_nbits;
+ num_xfers++;
+ }

- t[1].rx_buf = buf;
- t[1].rx_nbits = m25p80_rx_nbits(nor);
- t[1].len = len;
- spi_message_add_tail(&t[1], &m);
+ xfers[num_xfers].len = len;
+ xfers[num_xfers].rx_buf = buf;
+ xfers[num_xfers].rx_nbits = data_nbits;
+ num_xfers++;

+ /* Process command. */
+ spi_message_init_with_transfers(&m, xfers, num_xfers);
spi_sync(spi, &m);

*retlen = m.actual_length - m25p_cmdsz(nor) - dummy;
--
1.8.2.2