[RFC 1/3] usb: typec: tps6598x: handle block writes separately with plain-I2C adapters

[Suwan Kim <suwan.kim027@gmail.com>]

From: Nikolaus Voss <nikolaus.voss@loewensteinmedical.de>

Commit 1a2f474d328f handles block _reads_ separately with plain-I2C
adapters, but the problem described with regmap-i2c not handling
SMBus block transfers (i.e. read and writes) correctly also exists
with writes.

As workaround, this patch adds a block write function the same way
1a2f474d328f adds a block read function.

Fixes: 1a2f474d328f ("usb: typec: tps6598x: handle block reads separately with plain-I2C adapters")
Fixes: 0a4c005bd171 ("usb: typec: driver for TI TPS6598x USB Power Delivery controllers")
Signed-off-by: Nikolaus Voss <nikolaus.voss@loewensteinmedical.de>
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/typec/tps6598x.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/typec/tps6598x.c b/drivers/usb/typec/tps6598x.c
index 9947c87d2a1e..c674abe3cf99 100644
--- a/drivers/usb/typec/tps6598x.c
+++ b/drivers/usb/typec/tps6598x.c
@@ -126,6 +126,20 @@ tps6598x_block_read(struct tps6598x *tps, u8 reg, void *val, size_t len)
 	return 0;
 }
 
+static int tps6598x_block_write(struct tps6598x *tps, u8 reg,
+				void *val, size_t len)
+{
+	u8 data[TPS_MAX_LEN + 1];
+
+	if (!tps->i2c_protocol)
+		return regmap_raw_write(tps->regmap, reg, val, len);
+
+	data[0] = len;
+	memcpy(&data[1], val, len);
+
+	return regmap_raw_write(tps->regmap, reg, data, sizeof(data));
+}
+
 static inline int tps6598x_read16(struct tps6598x *tps, u8 reg, u16 *val)
 {
 	return tps6598x_block_read(tps, reg, val, sizeof(u16));
@@ -143,23 +157,23 @@ static inline int tps6598x_read64(struct tps6598x *tps, u8 reg, u64 *val)
 
 static inline int tps6598x_write16(struct tps6598x *tps, u8 reg, u16 val)
 {
-	return regmap_raw_write(tps->regmap, reg, &val, sizeof(u16));
+	return tps6598x_block_write(tps, reg, &val, sizeof(u16));
 }
 
 static inline int tps6598x_write32(struct tps6598x *tps, u8 reg, u32 val)
 {
-	return regmap_raw_write(tps->regmap, reg, &val, sizeof(u32));
+	return tps6598x_block_write(tps, reg, &val, sizeof(u32));
 }
 
 static inline int tps6598x_write64(struct tps6598x *tps, u8 reg, u64 val)
 {
-	return regmap_raw_write(tps->regmap, reg, &val, sizeof(u64));
+	return tps6598x_block_write(tps, reg, &val, sizeof(u64));
 }
 
 static inline int
 tps6598x_write_4cc(struct tps6598x *tps, u8 reg, const char *val)
 {
-	return regmap_raw_write(tps->regmap, reg, &val, sizeof(u32));
+	return tps6598x_block_write(tps, reg, &val, sizeof(u32));
 }
 
 static int tps6598x_read_partner_identity(struct tps6598x *tps)
@@ -245,8 +259,8 @@ static int tps6598x_exec_cmd(struct tps6598x *tps, const char *cmd,
 		return -EBUSY;
 
 	if (in_len) {
-		ret = regmap_raw_write(tps->regmap, TPS_REG_DATA1,
-				       in_data, in_len);
+		ret = tps6598x_block_write(tps, TPS_REG_DATA1,
+					   in_data, in_len);
 		if (ret)
 			return ret;
 	}
-- 
2.20.1