[PATCH v3] mfd: ntxec: Support for EC in Tolino Shine 2 HD

[Andreas Kemnade]

Add the version of the EC in the Tolino Shine 2 HD
to the supported versions. It seems not to have an RTC
and does not ack data written to it.
The vendor kernel happily ignores write errors, using
I2C via userspace i2c-set also shows the error.
So add a quirk to ignore that error.

PWM can be successfully configured despite of that error.

Signed-off-by: Andreas Kemnade <andr...@kemnade.info>
Reviewed-by: Jonathan Neuschäfer <j.neuschae...@gmx.net>
---
Changes in v3:
- remove have_rtc variable
- rename subdevices again

Changes in v2:
- more comments about stacking regmap construction
- fix accidential line removal
- better naming for subdevices
 drivers/mfd/ntxec.c       | 55 ++++++++++++++++++++++++++++++++++++---
 include/linux/mfd/ntxec.h |  1 +
 2 files changed, 53 insertions(+), 3 deletions(-)

diff --git a/drivers/mfd/ntxec.c b/drivers/mfd/ntxec.c
index 957de2b03529..ab6860ef3e9a 100644
--- a/drivers/mfd/ntxec.c
+++ b/drivers/mfd/ntxec.c
@@ -96,6 +96,38 @@ static struct notifier_block ntxec_restart_handler = {
        .priority = 128,
 };
 
+static int regmap_ignore_write(void *context,
+                              unsigned int reg, unsigned int val)
+
+{
+       struct regmap *regmap = context;
+
+       regmap_write(regmap, reg, val);
+
+       return 0;
+}
+
+static int regmap_wrap_read(void *context, unsigned int reg,
+                           unsigned int *val)
+{
+       struct regmap *regmap = context;
+
+       return regmap_read(regmap, reg, val);
+}
+
+/*
+ * Some firmware versions do not ack written data, add a wrapper. It
+ * is used to stack another regmap on top.
+ */
+static const struct regmap_config regmap_config_noack = {
+       .name = "ntxec_noack",
+       .reg_bits = 8,
+       .val_bits = 16,
+       .cache_type = REGCACHE_NONE,
+       .reg_write = regmap_ignore_write,
+       .reg_read = regmap_wrap_read
+};
+
 static const struct regmap_config regmap_config = {
        .name = "ntxec",
        .reg_bits = 8,
@@ -104,16 +136,22 @@ static const struct regmap_config regmap_config = {
        .val_format_endian = REGMAP_ENDIAN_BIG,
 };
 
-static const struct mfd_cell ntxec_subdevices[] = {
+static const struct mfd_cell ntxec_subdev[] = {
        { .name = "ntxec-rtc" },
        { .name = "ntxec-pwm" },
 };
 
+static const struct mfd_cell ntxec_subdev_no_rtc[] = {
+       { .name = "ntxec-pwm" },
+};
+
 static int ntxec_probe(struct i2c_client *client)
 {
        struct ntxec *ec;
        unsigned int version;
        int res;
+       const struct mfd_cell *subdevs = ntxec_subdev;
+       size_t n_subdevs = ARRAY_SIZE(ntxec_subdev);
 
        ec = devm_kmalloc(&client->dev, sizeof(*ec), GFP_KERNEL);
        if (!ec)
@@ -138,6 +176,16 @@ static int ntxec_probe(struct i2c_client *client)
        switch (version) {
        case NTXEC_VERSION_KOBO_AURA:
                break;
+       case NTXEC_VERSION_TOLINO_SHINE2:
+               subdevs = ntxec_subdev_no_rtc;
+               n_subdevs = ARRAY_SIZE(ntxec_subdev_no_rtc);
+               /* Another regmap stacked on top of the other */
+               ec->regmap = devm_regmap_init(ec->dev, NULL,
+                                             ec->regmap,
+                                             &regmap_config_noack);
+               if (IS_ERR(ec->regmap))
+                       return PTR_ERR(ec->regmap);
+               break;
        default:
                dev_err(ec->dev,
                        "Netronix embedded controller version %04x is not 
supported.\n",
@@ -181,8 +229,9 @@ static int ntxec_probe(struct i2c_client *client)
 
        i2c_set_clientdata(client, ec);
 
-       res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE, 
ntxec_subdevices,
-                                  ARRAY_SIZE(ntxec_subdevices), NULL, 0, NULL);
+       res = devm_mfd_add_devices(ec->dev, PLATFORM_DEVID_NONE,
+                                  subdevs, n_subdevs,
+                                  NULL, 0, NULL);
        if (res)
                dev_err(ec->dev, "Failed to add subdevices: %d\n", res);
 
diff --git a/include/linux/mfd/ntxec.h b/include/linux/mfd/ntxec.h
index 361204d125f1..26ab3b8eb612 100644
--- a/include/linux/mfd/ntxec.h
+++ b/include/linux/mfd/ntxec.h
@@ -33,5 +33,6 @@ static inline __be16 ntxec_reg8(u8 value)
 
 /* Known firmware versions */
 #define NTXEC_VERSION_KOBO_AURA        0xd726  /* found in Kobo Aura */
+#define NTXEC_VERSION_TOLINO_SHINE2 0xf110 /* found in Tolino Shine 2 HD */
 
 #endif
-- 
2.29.2