DS3232 RTC has 236 bytes of persistent memory.
Add RTC SRAM read and write access using
the NVMEM Framework.
Signed-off-by: Nandor Han <nandor.han@xxxxxxxxxxx>
---
Description
-----------
Provides DS3232 RTC SRAM access using NVMEM framework.
Testing
-------
The test was done on a custom board which contains a
DS3232 RTC device.
Kernel Version: 4.14.60 (Just for clarity, the patch is against master)
1. Verify that SRAM is accessible using NVMEM interface: PASS
`
# hexdump /sys/bus/nvmem/devices/ds3232_sram0/nvmem
0000000 0000 0000 0000 0000 0000 0000 0000 0000
*
00000e0
`
2. Modify the content.
`
# echo testing > /sys/bus/nvmem/devices/ds3232_sram0/nvmem
#
`
3. Power cycle the board and verify that contents are preserved: PASS
`
# hexdump -n 10 -C /sys/bus/nvmem/devices/ds3232_sram0/nvmem
00000000 74 65 73 74 69 6e 67 0a 00 00 |testing...|
0000000a
`
drivers/rtc/rtc-ds3232.c | 41 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 39 insertions(+), 2 deletions(-)
diff --git a/drivers/rtc/rtc-ds3232.c b/drivers/rtc/rtc-ds3232.c
index 7184e5145f12..fe615aedaa9a 100644
--- a/drivers/rtc/rtc-ds3232.c
+++ b/drivers/rtc/rtc-ds3232.c
@@ -24,6 +24,8 @@
#include <linux/regmap.h>
#include <linux/hwmon.h>
+#include "rtc-core.h"
+
#define DS3232_REG_SECONDS 0x00
#define DS3232_REG_MINUTES 0x01
#define DS3232_REG_HOURS 0x02
@@ -48,12 +50,17 @@
# define DS3232_REG_SR_A1F 0x01
#define DS3232_REG_TEMPERATURE 0x11
+#define DS3232_REG_SRAM_START 0x14
+#define DS3232_REG_SRAM_END 0xFF
+
+#define DS3232_REG_SRAM_SIZE 236
struct ds3232 {
struct device *dev;
struct regmap *regmap;
int irq;
struct rtc_device *rtc;
+ struct nvmem_config nvmem_cfg;
bool suspended;
};
@@ -461,6 +468,24 @@ static const struct rtc_class_ops ds3232_rtc_ops = {
.alarm_irq_enable = ds3232_alarm_irq_enable,
};
+static int ds3232_nvmem_read(void *priv, unsigned int offset, void *val,
+ size_t bytes)
+{
+ struct ds3232 *ds3232 = (struct ds3232 *)priv;
+
+ return regmap_bulk_read(ds3232->regmap, DS3232_REG_SRAM_START + offset,
+ val, bytes);
+}
+
+static int ds3232_nvmem_write(void *priv, unsigned int offset, void *val,
+ size_t bytes)
+{
+ struct ds3232 *ds3232 = (struct ds3232 *)priv;
+
+ return regmap_bulk_write(ds3232->regmap, DS3232_REG_SRAM_START + offset,
+ val, bytes);
+}
+
static int ds3232_probe(struct device *dev, struct regmap *regmap, int irq,
const char *name)
{
@@ -476,6 +501,14 @@ static int ds3232_probe(struct device *dev, struct regmap *regmap, int irq,
ds3232->dev = dev;
dev_set_drvdata(dev, ds3232);
+ ds3232->nvmem_cfg.name = "ds3232_sram";
+ ds3232->nvmem_cfg.stride = 1;
+ ds3232->nvmem_cfg.size = DS3232_REG_SRAM_SIZE;
+ ds3232->nvmem_cfg.word_size = 1;
+ ds3232->nvmem_cfg.reg_read = ds3232_nvmem_read;
+ ds3232->nvmem_cfg.reg_write = ds3232_nvmem_write;
+ ds3232->nvmem_cfg.priv = ds3232;
+
ret = ds3232_check_rtc_status(dev);
if (ret)
return ret;
@@ -490,6 +523,10 @@ static int ds3232_probe(struct device *dev, struct regmap *regmap, int irq,
if (IS_ERR(ds3232->rtc))
return PTR_ERR(ds3232->rtc);
+ ds3232->rtc->dev.of_node = dev->of_node;
+ ds3232->rtc->nvmem_config = &ds3232->nvmem_cfg;
+ rtc_nvmem_register(ds3232->rtc);
+
if (ds3232->irq > 0) {
ret = devm_request_threaded_irq(dev, ds3232->irq, NULL,
ds3232_irq,
@@ -542,7 +579,7 @@ static int ds3232_i2c_probe(struct i2c_client *client,
static const struct regmap_config config = {
.reg_bits = 8,
.val_bits = 8,
- .max_register = 0x13,
+ .max_register = DS3232_REG_SRAM_END,
};
regmap = devm_regmap_init_i2c(client, &config);
@@ -609,7 +646,7 @@ static int ds3234_probe(struct spi_device *spi)
static const struct regmap_config config = {
.reg_bits = 8,
.val_bits = 8,
- .max_register = 0x13,
+ .max_register = DS3232_REG_SRAM_END,
.write_flag_mask = 0x80,
};
struct regmap *regmap;
--
2.17.2
