[PATCH v3 1/2] hwmon: (pmbus) add a function to check the presence of a block register

[Adam Wujek <dev_public@xxxxxxxx>]

Other functions (like pmbus_check_byte_register) cannot be used to check
the presence of a block register, because it will generate error when PEC
is used.

Signed-off-by: Adam Wujek <dev_public@xxxxxxxx>
---
Notes:
  Changes in v2:
    - Use Phase 0xff when setting the page
  Changes in v3:
    - remove not needed initialization of a buffer
    - add checking the flag PMBUS_READ_STATUS_AFTER_FAILED_CHECK

 drivers/hwmon/pmbus/pmbus_core.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index acf78d0829d9..a1c70877ae68 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -421,6 +421,18 @@ static int _pmbus_read_byte_data(struct i2c_client *client, int page, int reg)
 	return pmbus_read_byte_data(client, page, reg);
 }

+static int pmbus_read_block_data(struct i2c_client *client, int page, u8 reg,
+				 char *data_buf)
+{
+	int rv;
+
+	rv = pmbus_set_page(client, page, 0xff);
+	if (rv < 0)
+		return rv;
+
+	return i2c_smbus_read_block_data(client, reg, data_buf);
+}
+
 static struct pmbus_sensor *pmbus_find_sensor(struct pmbus_data *data, int page,
 					      int reg)
 {
@@ -558,6 +570,22 @@ bool pmbus_check_word_register(struct i2c_client *client, int page, int reg)
 }
 EXPORT_SYMBOL_NS_GPL(pmbus_check_word_register, PMBUS);

+static bool pmbus_check_block_register(struct i2c_client *client, int page,
+				       int reg)
+{
+	int rv;
+	struct pmbus_data *data = i2c_get_clientdata(client);
+	char data_buf[I2C_SMBUS_BLOCK_MAX + 2];
+
+	rv = pmbus_read_block_data(client, page, reg, data_buf);
+	if (rv >= 0 && !(data->flags & PMBUS_SKIP_STATUS_CHECK))
+		rv = pmbus_check_status_cml(client);
+	if (rv < 0 && (data->flags & PMBUS_READ_STATUS_AFTER_FAILED_CHECK))
+		data->read_status(client, -1);
+	pmbus_clear_fault_page(client, -1);
+	return rv >= 0;
+}
+
 const struct pmbus_driver_info *pmbus_get_driver_info(struct i2c_client *client)
 {
 	struct pmbus_data *data = i2c_get_clientdata(client);
--
2.17.1