From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
Make sure the device we are probing is really the device we are
interested in.
Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
---
drivers/rtc/rtc-pcf2127.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c
index 241189ee4a05..e4b78b9c03f9 100644
--- a/drivers/rtc/rtc-pcf2127.c
+++ b/drivers/rtc/rtc-pcf2127.c
@@ -193,11 +193,13 @@ struct pcf21xx_config {
unsigned int has_nvmem:1;
unsigned int has_bit_wd_ctl_cd0:1;
unsigned int has_int_a_b:1; /* PCF2131 supports two interrupt outputs. */
+ unsigned int has_reset_reg:1; /* If variant has a reset register. */
u8 regs_td_base; /* Time/data base registers. */
u8 regs_alarm_base; /* Alarm function base registers. */
u8 reg_wd_ctl; /* Watchdog control register. */
u8 reg_wd_val; /* Watchdog value register. */
u8 reg_clkout; /* Clkout register. */
+ u8 reg_reset; /* Reset register if available. */
unsigned int ts_count;
struct pcf21xx_ts_config ts[4];
struct attribute_group attribute_group;
@@ -882,6 +884,7 @@ static struct pcf21xx_config pcf21xx_cfg[] = {
.has_nvmem = 1,
.has_bit_wd_ctl_cd0 = 1,
.has_int_a_b = 0,
+ .has_reset_reg = 0,
.regs_td_base = PCF2127_REG_TIME_DATE_BASE,
.regs_alarm_base = PCF2127_REG_ALARM_BASE,
.reg_wd_ctl = PCF2127_REG_WD_CTL,
@@ -906,6 +909,7 @@ static struct pcf21xx_config pcf21xx_cfg[] = {
.has_nvmem = 0,
.has_bit_wd_ctl_cd0 = 0,
.has_int_a_b = 0,
+ .has_reset_reg = 0,
.regs_td_base = PCF2127_REG_TIME_DATE_BASE,
.regs_alarm_base = PCF2127_REG_ALARM_BASE,
.reg_wd_ctl = PCF2127_REG_WD_CTL,
@@ -930,11 +934,13 @@ static struct pcf21xx_config pcf21xx_cfg[] = {
.has_nvmem = 0,
.has_bit_wd_ctl_cd0 = 0,
.has_int_a_b = 1,
+ .has_reset_reg = 1,
.regs_td_base = PCF2131_REG_TIME_DATE_BASE,
.regs_alarm_base = PCF2131_REG_ALARM_BASE,
.reg_wd_ctl = PCF2131_REG_WD_CTL,
.reg_wd_val = PCF2131_REG_WD_VAL,
.reg_clkout = PCF2131_REG_CLKOUT,
+ .reg_reset = PCF2131_REG_SR_RESET,
.ts_count = 4,
.ts[0] = {
.regs_base = PCF2131_REG_TS1_BASE,
@@ -1075,6 +1081,20 @@ static int pcf2127_probe(struct device *dev, struct regmap *regmap,
clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, pcf2127->rtc->features);
clear_bit(RTC_FEATURE_ALARM, pcf2127->rtc->features);
+ /* Read device signature if available. */
+ if (pcf2127->cfg->has_reset_reg) {
+ ret = regmap_read(pcf2127->regmap, pcf2127->cfg->reg_reset, &val);
+ if (ret < 0) {
+ dev_err(dev, "reading RESET register failed\n");
+ return ret;
+ }
+
+ if (val != PCF2131_SR_RESET_READ_PATTERN) {
+ dev_err(dev, "invalid device signature: $%02X\n", (u8)val);
+ return -ENODEV;
+ }
+ }
+
if (alarm_irq > 0) {
unsigned long flags;
--
2.30.2
