The open coded handling of attribute nvram is from 2007 when the
nvmem subsystem obviously didn't exist yet.
Now we can use nvmem to simplify the driver. A side effect is that
attribute nvram is replaced. New location is:
/sys/bus/nvmem/devices/ds1307_nvram0/nvmem
This might break user space applications. However attribute nvram
is nowhere officially documented and I'm not sure whether anybody
is actually using the few nvram bytes on a rtc chip.
This patch is compile-tested only as I lack hardware with nvram.
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
---
v2:
- embed nvmem_config structure part in struct ds1307
- set name and owner members of struct nvmem_config
v3:
- extend Kconfig help text
- use IS_REACHABLE to not access the NVMEM API if ds1307 is
built-in and NVMEM is a module. I don't use Kconfig dependencies
because only few supported chips have NVRAM.
---
drivers/rtc/Kconfig | 5 ++-
drivers/rtc/rtc-ds1307.c | 101 ++++++++++++++++++-----------------------------
2 files changed, 42 insertions(+), 64 deletions(-)
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 8d3b9572..22ac31fd 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -219,8 +219,9 @@ config RTC_DRV_DS1307
The first seven registers on these chips hold an RTC, and other
registers may add features such as NVRAM, a trickle charger for
- the RTC/NVRAM backup power, and alarms. NVRAM is visible in
- sysfs, but other chip features may not be available.
+ the RTC/NVRAM backup power, and alarms.
+ If your chip has NVRAM and CONFIG_NVMEM is set then the NVRAM
+ is accessible via sysfs.
This driver can also be built as a module. If so, the module
will be called rtc-ds1307.
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 79160027..a2a90cd2 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -25,6 +25,7 @@
#include <linux/hwmon-sysfs.h>
#include <linux/clk-provider.h>
#include <linux/regmap.h>
+#include <linux/nvmem-provider.h>
/*
* We can't determine type by probing, but if we expect pre-Linux code
@@ -116,11 +117,11 @@ struct ds1307 {
u8 offset; /* register's offset */
u8 regs[11];
u16 nvram_offset;
- struct bin_attribute *nvram;
+ struct nvmem_config nvram_cfg;
+ struct nvmem_device *nvram;
enum ds_type type;
unsigned long flags;
-#define HAS_NVRAM 0 /* bit 0 == sysfs file active */
-#define HAS_ALARM 1 /* bit 1 == irq claimed */
+#define HAS_ALARM 0 /* bit 0 == irq claimed */
struct device *dev;
struct regmap *regmap;
const char *name;
@@ -676,42 +677,27 @@ static const struct rtc_class_ops mcp794xx_rtc_ops = {
/*----------------------------------------------------------------------*/
-static ssize_t
-ds1307_nvram_read(struct file *filp, struct kobject *kobj,
- struct bin_attribute *attr,
- char *buf, loff_t off, size_t count)
-{
- struct ds1307 *ds1307;
- int result;
+#if IS_REACHABLE(CONFIG_NVMEM)
- ds1307 = dev_get_drvdata(kobj_to_dev(kobj));
+static int ds1307_nvram_read(void *priv, unsigned int offset, void *val,
+ size_t bytes)
+{
+ struct ds1307 *ds1307 = priv;
- result = regmap_bulk_read(ds1307->regmap, ds1307->nvram_offset + off,
- buf, count);
- if (result)
- dev_err(ds1307->dev, "%s error %d\n", "nvram read", result);
- return result;
+ return regmap_bulk_read(ds1307->regmap, ds1307->nvram_offset + offset,
+ val, bytes);
}
-static ssize_t
-ds1307_nvram_write(struct file *filp, struct kobject *kobj,
- struct bin_attribute *attr,
- char *buf, loff_t off, size_t count)
+static int ds1307_nvram_write(void *priv, unsigned int offset, void *val,
+ size_t bytes)
{
- struct ds1307 *ds1307;
- int result;
-
- ds1307 = dev_get_drvdata(kobj_to_dev(kobj));
+ struct ds1307 *ds1307 = priv;
- result = regmap_bulk_write(ds1307->regmap, ds1307->nvram_offset + off,
- buf, count);
- if (result) {
- dev_err(ds1307->dev, "%s error %d\n", "nvram write", result);
- return result;
- }
- return count;
+ return regmap_bulk_write(ds1307->regmap, ds1307->nvram_offset + offset,
+ val, bytes);
}
+#endif
/*----------------------------------------------------------------------*/
@@ -1475,39 +1461,28 @@ static int ds1307_probe(struct i2c_client *client,
dev_dbg(ds1307->dev, "got IRQ %d\n", client->irq);
}
+#if IS_REACHABLE(CONFIG_NVMEM)
if (chip->nvram_size) {
-
- ds1307->nvram = devm_kzalloc(ds1307->dev,
- sizeof(struct bin_attribute),
- GFP_KERNEL);
- if (!ds1307->nvram) {
- dev_err(ds1307->dev,
- "cannot allocate memory for nvram sysfs\n");
+ ds1307->nvram_cfg.name = "ds1307_nvram";
+ ds1307->nvram_cfg.dev = ds1307->dev;
+ ds1307->nvram_cfg.reg_read = ds1307_nvram_read;
+ ds1307->nvram_cfg.reg_write = ds1307_nvram_write;
+ ds1307->nvram_cfg.size = chip->nvram_size;
+ ds1307->nvram_cfg.word_size = 1;
+ ds1307->nvram_cfg.stride = 1;
+ ds1307->nvram_cfg.priv = ds1307;
+ ds1307->nvram_cfg.owner = THIS_MODULE;
+
+ ds1307->nvram = nvmem_register(&ds1307->nvram_cfg);
+ if (IS_ERR(ds1307->nvram)) {
+ dev_err(ds1307->dev, "unable to register nvmem\n");
+ ds1307->nvram = NULL;
} else {
-
- ds1307->nvram->attr.name = "nvram";
- ds1307->nvram->attr.mode = S_IRUGO | S_IWUSR;
-
- sysfs_bin_attr_init(ds1307->nvram);
-
- ds1307->nvram->read = ds1307_nvram_read;
- ds1307->nvram->write = ds1307_nvram_write;
- ds1307->nvram->size = chip->nvram_size;
- ds1307->nvram_offset = chip->nvram_offset;
-
- err = sysfs_create_bin_file(&ds1307->dev->kobj,
- ds1307->nvram);
- if (err) {
- dev_err(ds1307->dev,
- "unable to create sysfs file: %s\n",
- ds1307->nvram->attr.name);
- } else {
- set_bit(HAS_NVRAM, &ds1307->flags);
- dev_info(ds1307->dev, "%zu bytes nvram\n",
- ds1307->nvram->size);
- }
+ dev_info(ds1307->dev, "%d bytes nvram\n",
+ chip->nvram_size);
}
}
+#endif
ds1307_hwmon_register(ds1307);
ds1307_clks_register(ds1307);
@@ -1522,8 +1497,10 @@ static int ds1307_remove(struct i2c_client *client)
{
struct ds1307 *ds1307 = i2c_get_clientdata(client);
- if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
- sysfs_remove_bin_file(&ds1307->dev->kobj, ds1307->nvram);
+#if IS_REACHABLE(CONFIG_NVMEM)
+ if (ds1307->nvram)
+ nvmem_unregister(ds1307->nvram);
+#endif
return 0;
}
--
2.13.0
