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Subject: [PATCH 2/3] I2C: at24: add kernel interface for reading/writing EEPROM
Date: Monday 25 August 2008
From: Kevin Hilman <khilman@deeprootsystems.com>
To: davinci-linux-open-source@linux.davincidsp.com
This patch adds an interface by which other kernel code can read/write
detected EEPROM.
The platform code registers a 'setup' callback with the
at24_platform_data. When the at24 driver detects an EEPROM, it fills
out the read and write functions of at24_iface and calls the setup
callback. The platform code can then use the read/write functions in
the at24_iface struct for reading and writing the EEPROM.
Original idea, review and updates by David Brownell <david-b@pacbell.net>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
---
drivers/i2c/chips/at24.c | 42 +++++++++++++++++++++++++++++++++++-------
include/linux/i2c/at24.h | 10 ++++++++++
2 files changed, 45 insertions(+), 7 deletions(-)
--- a/drivers/i2c/chips/at24.c
+++ b/drivers/i2c/chips/at24.c
@@ -53,6 +53,7 @@
struct at24_data {
struct at24_platform_data chip;
+ struct at24_iface iface;
bool use_smbus;
/*
@@ -264,13 +265,6 @@ static ssize_t at24_bin_read(struct kobj
/*
- * REVISIT: export at24_bin{read,write}() to let other kernel code use
- * eeprom data. For example, it might hold a board's Ethernet address, or
- * board-specific calibration data generated on the manufacturing floor.
- */
-
-
-/*
* Note that if the hardware write-protect pin is pulled high, the whole
* chip is normally write protected. But there are plenty of product
* variants here, including OTP fuses and partial chip protect.
@@ -386,6 +380,30 @@ static ssize_t at24_bin_write(struct kob
/*-------------------------------------------------------------------------*/
+/*
+ * This lets other kernel code access the eeprom data. For example, it
+ * might hold a board's Ethernet address, or board-specific calibration
+ * data generated on the manufacturing floor.
+ */
+
+static ssize_t at24_iface_read(struct at24_iface *iface, char *buf,
+ off_t offset, size_t count)
+{
+ struct at24_data *at24 = container_of(iface, struct at24_data, iface);
+
+ return at24_eeprom_read(at24, buf, offset, count);
+}
+
+static ssize_t at24_iface_write(struct at24_iface *iface, char *buf,
+ off_t offset, size_t count)
+{
+ struct at24_data *at24 = container_of(iface, struct at24_data, iface);
+
+ return at24_eeprom_write(at24, buf, offset, count);
+}
+
+/*-------------------------------------------------------------------------*/
+
static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
struct at24_platform_data chip;
@@ -413,6 +431,9 @@ static int at24_probe(struct i2c_client
* is recommended anyhow.
*/
chip.page_size = 1;
+
+ chip.setup = NULL;
+ chip.context = NULL;
}
if (!is_power_of_2(chip.byte_len))
@@ -449,6 +470,9 @@ static int at24_probe(struct i2c_client
goto err_out;
}
+ at24->iface.read = at24_iface_read;
+ at24->iface.write = at24_iface_write;
+
mutex_init(&at24->lock);
at24->use_smbus = use_smbus;
at24->chip = chip;
@@ -521,6 +545,10 @@ static int at24_probe(struct i2c_client
at24->write_max,
use_smbus ? ", use_smbus" : "");
+ /* export data to kernel code */
+ if (chip.setup)
+ chip.setup(&at24->iface, chip.context);
+
return 0;
err_clients:
--- a/include/linux/i2c/at24.h
+++ b/include/linux/i2c/at24.h
@@ -15,6 +15,13 @@
* is bigger than what the chip actually supports!
*/
+struct at24_iface {
+ ssize_t (*read)(struct at24_iface *, char *buf, off_t offset,
+ size_t count);
+ ssize_t (*write)(struct at24_iface *, char *buf, off_t offset,
+ size_t count);
+};
+
struct at24_platform_data {
u32 byte_len; /* size (sum of all addr) */
u16 page_size; /* for writes */
@@ -23,6 +30,9 @@ struct at24_platform_data {
#define AT24_FLAG_READONLY 0x40 /* sysfs-entry will be read-only */
#define AT24_FLAG_IRUGO 0x20 /* sysfs-entry will be world-readable */
#define AT24_FLAG_TAKE8ADDR 0x10 /* take always 8 addresses (24c00) */
+
+ int (*setup)(struct at24_iface *, void *context);
+ void *context;
};
#endif /* _LINUX_AT24_H */
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