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Subject[PATCH v7 2/4] mtd: m25p80: add support of SPI 1-2-2 and 1-4-4 protocols
Date
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, m25p80_write() only supported SPI 1-1-1.

This patch updates both m25p80_read() and m25p80_write() functions to let
them support SPI 1-2-2 and SPI 1-4-4 protocols for Fast Read and Page
Program SPI commands.

It adopts a conservative approach to avoid regressions. Hence the new
implementations try to be as close as possible to the old implementations,
so the main differences are:
- the tx_nbits values now being set properly for the spi_transfer
structures carrying the (op code + address/dummy) bytes
- and the spi_transfer structure being split into 2 spi_transfer
structures when the numbers of I/O lines are different for op code and
for address/dummy byte transfers on the SPI bus.

Besides, the current spi-nor framework supports neither the SPI 2-2-2 nor
the SPI 4-4-4 protocols. So, for now, we don't need to update the
m25p80_{read|write}_reg() functions as SPI 1-1-1 is the only one possible
protocol.

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Reviewed-by: Marek Vasut <marek.vasut@gmail.com>
---
drivers/mtd/devices/m25p80.c | 102 +++++++++++++++++++++++++++++++++----------
1 file changed, 79 insertions(+), 23 deletions(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 07073f4ce0bd..00eea6fd379c 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -78,11 +78,17 @@ static ssize_t 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 int inst_nbits, addr_nbits, data_nbits, data_idx;
+ struct spi_transfer t[3] = {};
struct spi_message m;
int cmd_sz = m25p_cmdsz(nor);
ssize_t ret;

+ /* get transfer protocols. */
+ inst_nbits = spi_nor_get_protocol_inst_nbits(nor->write_proto);
+ addr_nbits = spi_nor_get_protocol_addr_nbits(nor->write_proto);
+ data_nbits = spi_nor_get_protocol_data_nbits(nor->write_proto);
+
spi_message_init(&m);

if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
@@ -92,12 +98,27 @@ static ssize_t m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
m25p_addr2cmd(nor, to, flash->command);

t[0].tx_buf = flash->command;
+ t[0].tx_nbits = inst_nbits;
t[0].len = cmd_sz;
spi_message_add_tail(&t[0], &m);

- t[1].tx_buf = buf;
- t[1].len = len;
- spi_message_add_tail(&t[1], &m);
+ /* split the op code and address bytes into two transfers if needed. */
+ data_idx = 1;
+ if (addr_nbits != inst_nbits) {
+ t[0].len = 1;
+
+ t[1].tx_buf = &flash->command[1];
+ t[1].tx_nbits = addr_nbits;
+ t[1].len = cmd_sz - 1;
+ spi_message_add_tail(&t[1], &m);
+
+ data_idx = 2;
+ }
+
+ t[data_idx].tx_buf = buf;
+ t[data_idx].tx_nbits = data_nbits;
+ t[data_idx].len = len;
+ spi_message_add_tail(&t[data_idx], &m);

ret = spi_sync(spi, &m);
if (ret)
@@ -109,11 +130,6 @@ static ssize_t m25p80_write(struct spi_nor *nor, loff_t to, size_t len,
return ret;
}

-static inline unsigned int m25p80_rx_nbits(struct spi_nor *nor)
-{
- return spi_nor_get_protocol_data_nbits(nor->read_proto);
-}
-
/*
* Read an address range from the nor chip. The address range
* may be any size provided it is within the physical boundaries.
@@ -123,13 +139,20 @@ static ssize_t 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];
+ unsigned int inst_nbits, addr_nbits, data_nbits, data_idx;
+ struct spi_transfer t[3];
struct spi_message m;
unsigned int dummy = nor->read_dummy;
ssize_t ret;
+ int cmd_sz;
+
+ /* get transfer protocols. */
+ inst_nbits = spi_nor_get_protocol_inst_nbits(nor->read_proto);
+ addr_nbits = spi_nor_get_protocol_addr_nbits(nor->read_proto);
+ data_nbits = spi_nor_get_protocol_data_nbits(nor->read_proto);

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

if (spi_flash_read_supported(spi)) {
struct spi_flash_read_message msg;
@@ -142,10 +165,9 @@ static ssize_t 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 = inst_nbits;
+ msg.addr_nbits = addr_nbits;
+ msg.data_nbits = data_nbits;

ret = spi_flash_read(spi, &msg);
if (ret < 0)
@@ -160,20 +182,45 @@ static ssize_t m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
m25p_addr2cmd(nor, from, flash->command);

t[0].tx_buf = flash->command;
+ t[0].tx_nbits = inst_nbits;
t[0].len = m25p_cmdsz(nor) + dummy;
spi_message_add_tail(&t[0], &m);

- t[1].rx_buf = buf;
- t[1].rx_nbits = m25p80_rx_nbits(nor);
- t[1].len = min3(len, spi_max_transfer_size(spi),
- spi_max_message_size(spi) - t[0].len);
- spi_message_add_tail(&t[1], &m);
+ /*
+ * Set all dummy/mode cycle bits to avoid sending some manufacturer
+ * specific pattern, which might make the memory enter its Continuous
+ * Read mode by mistake.
+ * Based on the different mode cycle bit patterns listed and described
+ * in the JESD216B specification, the 0xff value works for all memories
+ * and all manufacturers.
+ */
+ cmd_sz = t[0].len;
+ memset(flash->command + cmd_sz - dummy, 0xff, dummy);
+
+ /* split the op code and address bytes into two transfers if needed. */
+ data_idx = 1;
+ if (addr_nbits != inst_nbits) {
+ t[0].len = 1;
+
+ t[1].tx_buf = &flash->command[1];
+ t[1].tx_nbits = addr_nbits;
+ t[1].len = cmd_sz - 1;
+ spi_message_add_tail(&t[1], &m);
+
+ data_idx = 2;
+ }
+
+ t[data_idx].rx_buf = buf;
+ t[data_idx].rx_nbits = data_nbits;
+ t[data_idx].len = min3(len, spi_max_transfer_size(spi),
+ spi_max_message_size(spi) - cmd_sz);
+ spi_message_add_tail(&t[data_idx], &m);

ret = spi_sync(spi, &m);
if (ret)
return ret;

- ret = m.actual_length - m25p_cmdsz(nor) - dummy;
+ ret = m.actual_length - cmd_sz;
if (ret < 0)
return -EIO;
return ret;
@@ -218,11 +265,20 @@ static int m25p_probe(struct spi_device *spi)
spi_set_drvdata(spi, flash);
flash->spi = spi;

- if (spi->mode & SPI_RX_QUAD)
+ if (spi->mode & SPI_RX_QUAD) {
hwcaps.mask |= SNOR_HWCAPS_READ_1_1_4;
- else if (spi->mode & SPI_RX_DUAL)
+
+ if (spi->mode & SPI_TX_QUAD)
+ hwcaps.mask |= (SNOR_HWCAPS_READ_1_4_4 |
+ SNOR_HWCAPS_PP_1_1_4 |
+ SNOR_HWCAPS_PP_1_4_4);
+ } else if (spi->mode & SPI_RX_DUAL) {
hwcaps.mask |= SNOR_HWCAPS_READ_1_1_2;

+ if (spi->mode & SPI_TX_DUAL)
+ hwcaps.mask |= SNOR_HWCAPS_READ_1_2_2;
+ }
+
if (data && data->name)
nor->mtd.name = data->name;

--
2.9.3
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