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Message-ID: <49375a87-5eca-a1c3-26f9-81075dd9c7f9@gmail.com>
Date: Fri, 7 Apr 2017 01:37:04 +0200
From: Marek Vasut <marek.vasut@...il.com>
To: Cyrille Pitchen <cyrille.pitchen@...el.com>,
linux-mtd@...ts.infradead.org, jartur@...ence.com,
kdasu.kdev@...il.com, mar.krzeminski@...il.com
Cc: computersforpeace@...il.com, dwmw2@...radead.org,
boris.brezillon@...e-electrons.com, richard@....at,
linux-kernel@...r.kernel.org, nicolas.ferre@...rochip.com
Subject: Re: [PATCH v5 2/6] mtd: m25p80: add support of SPI 1-2-2 and 1-4-4
protocols
On 03/23/2017 12:33 AM, Cyrille Pitchen wrote:
> 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
^ FYI, regression != bug
> 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@...el.com>
> ---
> drivers/mtd/devices/m25p80.c | 120 ++++++++++++++++++++++++++++++++-----------
> 1 file changed, 90 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
> index 68986a26c8fe..64d562efc25d 100644
> --- a/drivers/mtd/devices/m25p80.c
> +++ b/drivers/mtd/devices/m25p80.c
> @@ -34,6 +34,19 @@ struct m25p {
> u8 command[MAX_CMD_SIZE];
> };
>
> +static inline void m25p80_proto2nbits(enum spi_nor_protocol proto,
> + unsigned int *inst_nbits,
> + unsigned int *addr_nbits,
> + unsigned int *data_nbits)
> +{
Why don't we just have some generic macros to extract the number of bits
from $proto ?
> + if (inst_nbits)
> + *inst_nbits = spi_nor_get_protocol_inst_width(proto);
> + if (addr_nbits)
> + *addr_nbits = spi_nor_get_protocol_addr_width(proto);
> + if (data_nbits)
> + *data_nbits = spi_nor_get_protocol_data_width(proto);
> +}
> +
> static int m25p80_read_reg(struct spi_nor *nor, u8 code, u8 *val, int len)
> {
> struct m25p *flash = nor->priv;
> @@ -78,11 +91,16 @@ 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. */
> + m25p80_proto2nbits(nor->write_proto, &inst_nbits,
> + &addr_nbits, &data_nbits);
> +
> spi_message_init(&m);
>
> if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
> @@ -92,12 +110,27 @@ 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)
> @@ -109,18 +142,6 @@ 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)
> -{
> - switch (nor->read_proto) {
> - case SNOR_PROTO_1_1_2:
> - return 2;
> - case SNOR_PROTO_1_1_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.
> @@ -130,13 +151,19 @@ 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. */
> + m25p80_proto2nbits(nor->read_proto, &inst_nbits,
> + &addr_nbits, &data_nbits);
>
> /* 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;
> @@ -149,10 +176,9 @@ 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)
> @@ -167,20 +193,45 @@ 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 speficication, the 0xff value works for all memories
^
specification, typo
> + * 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;
> @@ -223,11 +274,20 @@ 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;
>
>
--
Best regards,
Marek Vasut
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