The old RTC7301 driver in OpenWrt used byte access, but the
current mainline Linux driver uses 32bit word access.
Make this configurable using device properties using the
standard property "reg-io-width" in e.g. device tree.
This is needed for the USRobotics USR8200 which has the
chip connected using byte accesses.
Debugging and testing by Howard Harte.
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
drivers/rtc/rtc-r7301.c | 35 +++++++++++++++++++++++++++++++++--
1 file changed, 33 insertions(+), 2 deletions(-)
diff --git a/drivers/rtc/rtc-r7301.c b/drivers/rtc/rtc-r7301.c
index 5dbaeb7af648..ef913cf8593f 100644
--- a/drivers/rtc/rtc-r7301.c
+++ b/drivers/rtc/rtc-r7301.c
@@ -14,6 +14,7 @@
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/delay.h>
+#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
@@ -55,12 +56,23 @@ struct rtc7301_priv {
u8 bank;
};
-static const struct regmap_config rtc7301_regmap_config = {
+/*
+ * When the device is memory-mapped, some platforms pack the registers into
+ * 32-bit access using the lower 8 bits at each 4-byte stride, while others
+ * expose them as simply consecutive bytes.
+ */
+static const struct regmap_config rtc7301_regmap_32_config = {
.reg_bits = 32,
.val_bits = 8,
.reg_stride = 4,
};
+static const struct regmap_config rtc7301_regmap_8_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .reg_stride = 1,
+};
+
static u8 rtc7301_read(struct rtc7301_priv *priv, unsigned int reg)
{
int reg_stride = regmap_get_reg_stride(priv->regmap);
@@ -356,7 +368,9 @@ static int __init rtc7301_rtc_probe(struct platform_device *dev)
void __iomem *regs;
struct rtc7301_priv *priv;
struct rtc_device *rtc;
+ static const struct regmap_config *mapconf;
int ret;
+ u32 val;
priv = devm_kzalloc(&dev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
@@ -366,8 +380,25 @@ static int __init rtc7301_rtc_probe(struct platform_device *dev)
if (IS_ERR(regs))
return PTR_ERR(regs);
+ ret = device_property_read_u32(&dev->dev, "reg-io-width", &val);
+ if (ret)
+ /* Default to 32bit accesses */
+ val = 4;
+
+ switch (val) {
+ case 1:
+ mapconf = &rtc7301_regmap_8_config;
+ break;
+ case 4:
+ mapconf = &rtc7301_regmap_32_config;
+ break;
+ default:
+ dev_err(&dev->dev, "invalid reg-io-width %d\n", val);
+ return -EINVAL;
+ }
+
priv->regmap = devm_regmap_init_mmio(&dev->dev, regs,
- &rtc7301_regmap_config);
+ mapconf);
if (IS_ERR(priv->regmap))
return PTR_ERR(priv->regmap);
--
2.41.0
