[PATCH V5] mtd: m25p80: Make fast read configurable via DT
Marek Vasut
marex at denx.de
Tue Sep 18 00:10:28 EST 2012
Bump, do you think we can get this into 3.7 please?
> Add DT property "m25p,fast-read" that signalises the particular
> chip supports "fast read" opcode.
>
> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
> Cc: David Woodhouse <david.woodhouse at intel.com>
> ---
> Documentation/devicetree/bindings/mtd/m25p80.txt | 29 ++++++++++++++++++
> drivers/mtd/devices/m25p80.c | 34
> +++++++++++++--------- 2 files changed, 50 insertions(+), 13 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/mtd/m25p80.txt
>
> V2: Add documentation for the DT property.
> V3: Use of_property_get_bool() instead of of_find_property().
> V4: Adjust the documentation's "compatible:" section, make it not
> Linux-specific, but keep the reference to Linux's list of
> supported devices. Also, use the default name, spansion,m25p80
> in the example.
> V5: Enclose of_property_read_bool() into CONFIG_OF for systems that do not
> use OF / Device Tree .
>
> diff --git a/Documentation/devicetree/bindings/mtd/m25p80.txt
> b/Documentation/devicetree/bindings/mtd/m25p80.txt new file mode 100644
> index 0000000..701bb58
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/m25p80.txt
> @@ -0,0 +1,29 @@
> +* MTD SPI driver for ST M25Pxx (and similar) serial flash chips
> +
> +Required properties:
> +- #address-cells, #size-cells : Must be present if the device has
> sub-nodes + representing partitions.
> +- compatible : Should be the manufacturer and the name of the chip. Bear
> in mind + the DT binding is not Linux-only, but in case of
> Linux, see the + "m25p_ids" table in
> drivers/mtd/devices/m25p80.c for the list of + supported
> chips.
> +- reg : Chip-Select number
> +- spi-max-frequency : Maximum frequency of the SPI bus the chip can
> operate at +
> +Optional properties:
> +- m25p,fast-read : Use the "fast read" opcode to read data from the chip
> instead + of the usual "read" opcode. This opcode isn
> not supported by + all chips and support for it can not
> be detected at runtime. + Refer to your chips' datasheet
> to check if this is supported + by your chip.
> +
> +Example:
> +
> + flash: m25p80 at 0 {
> + #address-cells = <1>;
> + #size-cells = <1>;
> + compatible = "spansion,m25p80";
> + reg = <0>;
> + spi-max-frequency = <40000000>;
> + m25p,fast-read;
> + };
> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
> index d16f75c..c433051 100644
> --- a/drivers/mtd/devices/m25p80.c
> +++ b/drivers/mtd/devices/m25p80.c
> @@ -73,14 +73,6 @@
> #define MAX_READY_WAIT_JIFFIES (40 * HZ) /* M25P16 specs 40s max
chip
> erase */ #define MAX_CMD_SIZE 5
>
> -#ifdef CONFIG_M25PXX_USE_FAST_READ
> -#define OPCODE_READ OPCODE_FAST_READ
> -#define FAST_READ_DUMMY_BYTE 1
> -#else
> -#define OPCODE_READ OPCODE_NORM_READ
> -#define FAST_READ_DUMMY_BYTE 0
> -#endif
> -
> #define JEDEC_MFR(_jedec_id) ((_jedec_id) >> 16)
>
> /*************************************************************************
> ***/ @@ -93,6 +85,7 @@ struct m25p {
> u16 addr_width;
> u8 erase_opcode;
> u8 *command;
> + bool fast_read;
> };
>
> static inline struct m25p *mtd_to_m25p(struct mtd_info *mtd)
> @@ -342,6 +335,7 @@ static int m25p80_read(struct mtd_info *mtd, loff_t
> from, size_t len, struct m25p *flash = mtd_to_m25p(mtd);
> struct spi_transfer t[2];
> struct spi_message m;
> + uint8_t opcode;
>
> pr_debug("%s: %s from 0x%08x, len %zd\n", dev_name(&flash->spi->dev),
> __func__, (u32)from, len);
> @@ -354,7 +348,7 @@ static int m25p80_read(struct mtd_info *mtd, loff_t
> from, size_t len, * Should add 1 byte DUMMY_BYTE.
> */
> t[0].tx_buf = flash->command;
> - t[0].len = m25p_cmdsz(flash) + FAST_READ_DUMMY_BYTE;
> + t[0].len = m25p_cmdsz(flash) + (flash->fast_read ? 1 : 0);
> spi_message_add_tail(&t[0], &m);
>
> t[1].rx_buf = buf;
> @@ -376,12 +370,14 @@ static int m25p80_read(struct mtd_info *mtd, loff_t
> from, size_t len, */
>
> /* Set up the write data buffer. */
> - flash->command[0] = OPCODE_READ;
> + opcode = flash->fast_read ? OPCODE_FAST_READ : OPCODE_NORM_READ;
> + flash->command[0] = opcode;
> m25p_addr2cmd(flash, from, flash->command);
>
> spi_sync(flash->spi, &m);
>
> - *retlen = m.actual_length - m25p_cmdsz(flash) - FAST_READ_DUMMY_BYTE;
> + *retlen = m.actual_length - m25p_cmdsz(flash) -
> + (flash->fast_read ? 1 : 0);
>
> mutex_unlock(&flash->lock);
>
> @@ -804,9 +800,10 @@ static int __devinit m25p_probe(struct spi_device
> *spi) struct flash_info *info;
> unsigned i;
> struct mtd_part_parser_data ppdata;
> + struct device_node *np = spi->dev.of_node;
>
> #ifdef CONFIG_MTD_OF_PARTS
> - if (!of_device_is_available(spi->dev.of_node))
> + if (!of_device_is_available(np))
> return -ENODEV;
> #endif
>
> @@ -858,7 +855,8 @@ static int __devinit m25p_probe(struct spi_device *spi)
> flash = kzalloc(sizeof *flash, GFP_KERNEL);
> if (!flash)
> return -ENOMEM;
> - flash->command = kmalloc(MAX_CMD_SIZE + FAST_READ_DUMMY_BYTE,
> GFP_KERNEL); + flash->command = kmalloc(MAX_CMD_SIZE + (flash-
>fast_read ?
> 1 : 0), + GFP_KERNEL);
> if (!flash->command) {
> kfree(flash);
> return -ENOMEM;
> @@ -915,6 +913,16 @@ static int __devinit m25p_probe(struct spi_device
> *spi) flash->page_size = info->page_size;
> flash->mtd.writebufsize = flash->page_size;
>
> + flash->fast_read = false;
> +#ifdef CONFIG_OF
> + if (np && of_property_read_bool(np, "m25p,fast-read"))
> + flash->fast_read = true;
> +#endif
> +
> +#ifdef CONFIG_M25PXX_USE_FAST_READ
> + flash->fast_read = true;
> +#endif
> +
> if (info->addr_width)
> flash->addr_width = info->addr_width;
> else {
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