diff options
author | Aswath Govindraju <a-govindraju@ti.com> | 2021-01-05 16:28:12 +0530 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-03-11 14:05:02 +0100 |
commit | 3399db28b4957a3229c67d080225d5203f849b2b (patch) | |
tree | 0b7b52e8a6861bd5fe3cc500a49d603592ed0e15 /drivers | |
parent | 545bb7b5639838d87a31ce4d5bef1a979ed16c83 (diff) | |
download | linux-stable-3399db28b4957a3229c67d080225d5203f849b2b.tar.gz linux-stable-3399db28b4957a3229c67d080225d5203f849b2b.tar.bz2 linux-stable-3399db28b4957a3229c67d080225d5203f849b2b.zip |
misc: eeprom_93xx46: Add quirk to support Microchip 93LC46B eeprom
[ Upstream commit f6f1f8e6e3eea25f539105d48166e91f0ab46dd1 ]
A dummy zero bit is sent preceding the data during a read transfer by the
Microchip 93LC46B eeprom (section 2.7 of[1]). This results in right shift
of data during a read. In order to ignore this bit a quirk can be added to
send an extra zero bit after the read address.
Add a quirk to ignore the zero bit sent before data by adding a zero bit
after the read address.
[1] - https://www.mouser.com/datasheet/2/268/20001749K-277859.pdf
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Link: https://lore.kernel.org/r/20210105105817.17644-3-a-govindraju@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/misc/eeprom/eeprom_93xx46.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/drivers/misc/eeprom/eeprom_93xx46.c b/drivers/misc/eeprom/eeprom_93xx46.c index a3248ebd28c6..182feab6da25 100644 --- a/drivers/misc/eeprom/eeprom_93xx46.c +++ b/drivers/misc/eeprom/eeprom_93xx46.c @@ -38,6 +38,10 @@ static const struct eeprom_93xx46_devtype_data atmel_at93c46d_data = { EEPROM_93XX46_QUIRK_INSTRUCTION_LENGTH, }; +static const struct eeprom_93xx46_devtype_data microchip_93lc46b_data = { + .quirks = EEPROM_93XX46_QUIRK_EXTRA_READ_CYCLE, +}; + struct eeprom_93xx46_dev { struct spi_device *spi; struct eeprom_93xx46_platform_data *pdata; @@ -58,6 +62,11 @@ static inline bool has_quirk_instruction_length(struct eeprom_93xx46_dev *edev) return edev->pdata->quirks & EEPROM_93XX46_QUIRK_INSTRUCTION_LENGTH; } +static inline bool has_quirk_extra_read_cycle(struct eeprom_93xx46_dev *edev) +{ + return edev->pdata->quirks & EEPROM_93XX46_QUIRK_EXTRA_READ_CYCLE; +} + static int eeprom_93xx46_read(void *priv, unsigned int off, void *val, size_t count) { @@ -99,6 +108,11 @@ static int eeprom_93xx46_read(void *priv, unsigned int off, dev_dbg(&edev->spi->dev, "read cmd 0x%x, %d Hz\n", cmd_addr, edev->spi->max_speed_hz); + if (has_quirk_extra_read_cycle(edev)) { + cmd_addr <<= 1; + bits += 1; + } + spi_message_init(&m); t[0].tx_buf = (char *)&cmd_addr; @@ -366,6 +380,7 @@ static void select_deassert(void *context) static const struct of_device_id eeprom_93xx46_of_table[] = { { .compatible = "eeprom-93xx46", }, { .compatible = "atmel,at93c46d", .data = &atmel_at93c46d_data, }, + { .compatible = "microchip,93lc46b", .data = µchip_93lc46b_data, }, {} }; MODULE_DEVICE_TABLE(of, eeprom_93xx46_of_table); |