From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Aswath Govindraju <a-govindraju@ti.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sasha Levin <sashal@kernel.org>
Subject: [PATCH AUTOSEL 4.14 09/13] misc: eeprom_93xx46: Add quirk to support Microchip 93LC46B eeprom
Date: Tue, 2 Mar 2021 06:58:59 -0500 [thread overview]
Message-ID: <20210302115903.63458-9-sashal@kernel.org> (raw)
In-Reply-To: <20210302115903.63458-1-sashal@kernel.org>
From: Aswath Govindraju <a-govindraju@ti.com>
[ 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>
---
drivers/misc/eeprom/eeprom_93xx46.c | 15 +++++++++++++++
include/linux/eeprom_93xx46.h | 2 ++
2 files changed, 17 insertions(+)
diff --git a/drivers/misc/eeprom/eeprom_93xx46.c b/drivers/misc/eeprom/eeprom_93xx46.c
index 38766968bfa2..0bcb1864eb5d 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);
diff --git a/include/linux/eeprom_93xx46.h b/include/linux/eeprom_93xx46.h
index eec7928ff8fe..99580c22f91a 100644
--- a/include/linux/eeprom_93xx46.h
+++ b/include/linux/eeprom_93xx46.h
@@ -16,6 +16,8 @@ struct eeprom_93xx46_platform_data {
#define EEPROM_93XX46_QUIRK_SINGLE_WORD_READ (1 << 0)
/* Instructions such as EWEN are (addrlen + 2) in length. */
#define EEPROM_93XX46_QUIRK_INSTRUCTION_LENGTH (1 << 1)
+/* Add extra cycle after address during a read */
+#define EEPROM_93XX46_QUIRK_EXTRA_READ_CYCLE BIT(2)
/*
* optional hooks to control additional logic
--
2.30.1
next prev parent reply other threads:[~2021-03-02 16:39 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-02 11:58 [PATCH AUTOSEL 4.14 01/13] udf: fix silent AED tagLocation corruption Sasha Levin
2021-03-02 11:58 ` [PATCH AUTOSEL 4.14 02/13] mmc: mxs-mmc: Fix a resource leak in an error handling path in 'mxs_mmc_probe()' Sasha Levin
2021-03-02 11:58 ` [PATCH AUTOSEL 4.14 03/13] mmc: mediatek: fix race condition between msdc_request_timeout and irq Sasha Levin
2021-03-02 11:58 ` [PATCH AUTOSEL 4.14 04/13] powerpc: improve handling of unrecoverable system reset Sasha Levin
2021-03-02 11:58 ` [PATCH AUTOSEL 4.14 05/13] powerpc/perf: Record counter overflow always if SAMPLE_IP is unset Sasha Levin
2021-03-02 11:58 ` [PATCH AUTOSEL 4.14 06/13] sparc32: Limit memblock allocation to low memory Sasha Levin
2021-03-03 8:19 ` Andreas Larsson
2021-03-12 22:13 ` Sasha Levin
2021-03-02 11:58 ` [PATCH AUTOSEL 4.14 07/13] x86, build: use objtool mcount Sasha Levin
2021-03-02 11:58 ` [PATCH AUTOSEL 4.14 08/13] PCI: xgene-msi: Fix race in installing chained irq handler Sasha Levin
2021-03-02 11:58 ` Sasha Levin [this message]
2021-03-02 11:59 ` [PATCH AUTOSEL 4.14 10/13] PCI: mediatek: Add missing of_node_put() to fix reference leak Sasha Levin
2021-03-02 11:59 ` [PATCH AUTOSEL 4.14 11/13] drm/msm/a5xx: Remove overwriting A5XX_PC_DBG_ECO_CNTL register Sasha Levin
2021-03-02 11:59 ` [PATCH AUTOSEL 4.14 12/13] s390/smp: __smp_rescan_cpus() - move cpumask away from stack Sasha Levin
2021-03-02 11:59 ` [PATCH AUTOSEL 4.14 13/13] scsi: libiscsi: Fix iscsi_prep_scsi_cmd_pdu() error handling Sasha Levin
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