rtc: pcf2127: add support for accessing internal static RAM

The PCF2127 has 512 bytes of internal static RAM and this patch expands
the driver to access this memory.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

1 files changed, 62 insertions, 6 deletions

diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
index e83be1852c2f..9f99a0966550 100644
--- a/drivers/rtc/rtc-pcf2127.c
+++ b/drivers/rtc/rtc-pcf2127.c
@@ -36,6 +36,11 @@
 #define PCF2127_REG_MO          (0x08)
 #define PCF2127_REG_YR          (0x09)
 
+/* the pcf2127 has 512 bytes nvmem, pcf2129 doesn't */
+#define PCF2127_REG_RAM_addr_MSB       0x1a
+#define PCF2127_REG_RAM_wrt_cmd        0x1c
+#define PCF2127_REG_RAM_rd_cmd         0x1d
+
 #define PCF2127_OSF             BIT(7)  /* Oscillator Fail flag */
 
 struct pcf2127 {
@@ -183,10 +188,47 @@ static const struct rtc_class_ops pcf2127_rtc_ops = {
         .set_time       = pcf2127_rtc_set_time,
 };
 
+static int pcf2127_nvmem_read(void *priv, unsigned int offset,
+                              void *val, size_t bytes)
+{
+        struct pcf2127 *pcf2127 = priv;
+        int ret;
+        unsigned char offsetbuf[] = { offset >> 8, offset };
+
+        ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_addr_MSB,
+                                offsetbuf, 2);
+        if (ret)
+                return ret;
+
+        ret = regmap_bulk_read(pcf2127->regmap, PCF2127_REG_RAM_rd_cmd,
+                               val, bytes);
+
+        return ret ?: bytes;
+}
+
+static int pcf2127_nvmem_write(void *priv, unsigned int offset,
+                               void *val, size_t bytes)
+{
+        struct pcf2127 *pcf2127 = priv;
+        int ret;
+        unsigned char offsetbuf[] = { offset >> 8, offset };
+
+        ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_addr_MSB,
+                                offsetbuf, 2);
+        if (ret)
+                return ret;
+
+        ret = regmap_bulk_write(pcf2127->regmap, PCF2127_REG_RAM_wrt_cmd,
+                                val, bytes);
+
+        return ret ?: bytes;
+}
+
 static int pcf2127_probe(struct device *dev, struct regmap *regmap,
-                        const char *name)
+                        const char *name, bool has_nvmem)
 {
         struct pcf2127 *pcf2127;
+        int ret = 0;
 
         dev_dbg(dev, "%s\n", __func__);
 
@@ -200,8 +242,21 @@ static int pcf2127_probe(struct device *dev, struct regmap *regmap,
 
         pcf2127->rtc = devm_rtc_device_register(dev, name, &pcf2127_rtc_ops,
                                                 THIS_MODULE);
+        if (IS_ERR(pcf2127->rtc))
+                return PTR_ERR(pcf2127->rtc);
+
+        if (has_nvmem) {
+                struct nvmem_config nvmem_cfg = {
+                        .priv = pcf2127,
+                        .reg_read = pcf2127_nvmem_read,
+                        .reg_write = pcf2127_nvmem_write,
+                        .size = 512,
+                };
+
+                ret = rtc_nvmem_register(pcf2127->rtc, &nvmem_cfg);
+        }
 
-        return PTR_ERR_OR_ZERO(pcf2127->rtc);
+        return ret;
 }
 
 #ifdef CONFIG_OF
@@ -309,11 +364,11 @@ static int pcf2127_i2c_probe(struct i2c_client *client,
         }
 
         return pcf2127_probe(&client->dev, regmap,
-                                pcf2127_i2c_driver.driver.name);
+                             pcf2127_i2c_driver.driver.name, id->driver_data);
 }
 
 static const struct i2c_device_id pcf2127_i2c_id[] = {
-        { "pcf2127", 0 },
+        { "pcf2127", 1 },
         { "pcf2129", 0 },
         { }
 };
@@ -372,11 +427,12 @@ static int pcf2127_spi_probe(struct spi_device *spi)
                 return PTR_ERR(regmap);
         }
 
-        return pcf2127_probe(&spi->dev, regmap, pcf2127_spi_driver.driver.name);
+        return pcf2127_probe(&spi->dev, regmap, pcf2127_spi_driver.driver.name,
+                             spi_get_device_id(spi)->driver_data);
 }
 
 static const struct spi_device_id pcf2127_spi_id[] = {
-        { "pcf2127", 0 },
+        { "pcf2127", 1 },
         { "pcf2129", 0 },
         { }
 };