Add "eeprom-nc" sysfs attribute to provide non-cached read access
to EEPROM data. This is needed because some EEPROM-like devices
contain constantly changing real-time diagnostic data that cannot
be cached in kernel memory.
Signed-off-by: Petri Gynther <pgynther@xxxxxxxxxx>
---
drivers/misc/eeprom/eeprom.c | 30 +++++++++++++++++++++++++++---
1 files changed, 27 insertions(+), 3 deletions(-)
diff --git a/drivers/misc/eeprom/eeprom.c b/drivers/misc/eeprom/eeprom.c
index 2c27193..101260b 100644
--- a/drivers/misc/eeprom/eeprom.c
+++ b/drivers/misc/eeprom/eeprom.c
@@ -39,6 +39,10 @@ I2C_CLIENT_INSMOD_1(eeprom);
/* Size of EEPROM in bytes */
#define EEPROM_SIZE 256
+/* EEPROM read modes */
+#define EEPROM_READ_CACHED 0
+#define EEPROM_READ_NONCACHED 1
+
/* possible types of eeprom devices */
enum eeprom_nature {
UNKNOWN,
@@ -55,14 +59,16 @@ struct eeprom_data {
};
-static void eeprom_update_client(struct i2c_client *client, u8 slice)
+static void eeprom_update_client(struct i2c_client *client, u8 slice,
+ int eeprom_read_mode)
{
struct eeprom_data *data = i2c_get_clientdata(client);
int i;
mutex_lock(&data->update_lock);
- if (!(data->valid & (1 << slice)) ||
+ if (eeprom_read_mode == EEPROM_READ_NONCACHED ||
+ !(data->valid & (1 << slice)) ||
time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);
@@ -102,7 +108,7 @@ static ssize_t eeprom_read(struct kobject *kobj, struct bin_attribute *bin_attr,
/* Only refresh slices which contain requested bytes */
for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
- eeprom_update_client(client, slice);
+ eeprom_update_client(client, slice, (int)bin_attr->private);
/* Hide Vaio private settings to regular users:
- BIOS passwords: bytes 0x00 to 0x0f
@@ -132,6 +138,17 @@ static struct bin_attribute eeprom_attr = {
},
.size = EEPROM_SIZE,
.read = eeprom_read,
+ .private = (void *)EEPROM_READ_CACHED,
+};
+
+static struct bin_attribute eeprom_nc_attr = {
+ .attr = {
+ .name = "eeprom-nc",
+ .mode = S_IRUGO,
+ },
+ .size = EEPROM_SIZE,
+ .read = eeprom_read,
+ .private = (void *)EEPROM_READ_NONCACHED,
};
/* Return 0 if detection is successful, -ENODEV otherwise */
@@ -202,8 +219,14 @@ static int eeprom_probe(struct i2c_client *client,
if (err)
goto exit_kfree;
+ err = sysfs_create_bin_file(&client->dev.kobj, &eeprom_nc_attr);
+ if (err)
+ goto exit_sysfs_clean;
+
return 0;
+exit_sysfs_clean:
+ sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);
exit_kfree:
kfree(data);
exit:
@@ -212,6 +235,7 @@ exit:
static int eeprom_remove(struct i2c_client *client)
{
+ sysfs_remove_bin_file(&client->dev.kobj, &eeprom_nc_attr);
sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);
kfree(i2c_get_clientdata(client));
--
1.5.4.3
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