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authorAswath Govindraju <a-govindraju@ti.com>2021-01-05 16:28:12 +0530
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-01-20 18:52:12 +0100
commitf6f1f8e6e3eea25f539105d48166e91f0ab46dd1 (patch)
treec35ff34709cdfb1bf2949e9a289e7632f2c86d4c /drivers/misc/eeprom
parent6805822954f0fd24de4d6febc4c84afdcb6f9baa (diff)
misc: eeprom_93xx46: Add quirk to support Microchip 93LC46B eeprom
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>
Diffstat (limited to 'drivers/misc/eeprom')
-rw-r--r--drivers/misc/eeprom/eeprom_93xx46.c15
1 files changed, 15 insertions, 0 deletions
diff --git a/drivers/misc/eeprom/eeprom_93xx46.c b/drivers/misc/eeprom/eeprom_93xx46.c
index e130a0d858e9..80114f4c80ad 100644
--- a/drivers/misc/eeprom/eeprom_93xx46.c
+++ b/drivers/misc/eeprom/eeprom_93xx46.c
@@ -35,6 +35,10 @@ 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;
@@ -55,6 +59,11 @@ 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)
{
@@ -96,6 +105,11 @@ 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;
@@ -363,6 +377,7 @@ 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 = &microchip_93lc46b_data, },
{}
};
MODULE_DEVICE_TABLE(of, eeprom_93xx46_of_table);