linux-kernel - [PATCH v2 2/4] hwmon: (pmbus): Access word data for STATUS

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Date:   Thu, 10 Aug 2017 16:57:48 -0500
From:   Eddie James <eajames@...ux.vnet.ibm.com>
To:     linux@...ck-us.net
Cc:     jdelvare@...e.com, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org, joel@....id.au, jk@...abs.org,
        andrew@...id.au, cbostic@...ux.vnet.ibm.com,
        eajames@...ux.vnet.ibm.com, "Edward A. James" <eajames@...ibm.com>
Subject: [PATCH v2 2/4] hwmon: (pmbus): Access word data for STATUS_WORD

From: "Edward A. James" <eajames@...ibm.com>

Pmbus always reads byte data from the status register, even if
configured to use STATUS_WORD. Use a function pointer to read the
correct amount of data from the registers.
Also switch to try STATUS_WORD first before STATUS_BYTE on init.

Signed-off-by: Edward A. James <eajames@...ibm.com>
---
 drivers/hwmon/pmbus/pmbus_core.c | 54 +++++++++++++++++++++++++++++-----------
 1 file changed, 40 insertions(+), 14 deletions(-)

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 4ec7586..277d170 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -113,7 +113,8 @@ struct pmbus_data {
 	 * so we keep them all together.
 	 */
 	u16 status[PB_NUM_STATUS_REG];
-	u8 status_register;
+
+	int (*read_status)(struct i2c_client *client, int page);
 
 	u8 currpage;
 };
@@ -324,7 +325,7 @@ static int pmbus_check_status_cml(struct i2c_client *client)
 	struct pmbus_data *data = i2c_get_clientdata(client);
 	int status, status2;
 
-	status = _pmbus_read_byte_data(client, -1, data->status_register);
+	status = data->read_status(client, -1);
 	if (status < 0 || (status & PB_STATUS_CML)) {
 		status2 = _pmbus_read_byte_data(client, -1, PMBUS_STATUS_CML);
 		if (status2 < 0 || (status2 & PB_CML_FAULT_INVALID_COMMAND))
@@ -348,6 +349,23 @@ static bool pmbus_check_register(struct i2c_client *client,
 	return rv >= 0;
 }
 
+static bool pmbus_check_status_register(struct i2c_client *client, int page)
+{
+	int status;
+	struct pmbus_data *data = i2c_get_clientdata(client);
+
+	status = data->read_status(client, page);
+	if (status >= 0 && !(data->flags & PMBUS_SKIP_STATUS_CHECK) &&
+	    (status & PB_STATUS_CML)) {
+		status = _pmbus_read_byte_data(client, -1, PMBUS_STATUS_CML);
+		if (status < 0 || (status & PB_CML_FAULT_INVALID_COMMAND))
+			status = -EIO;
+	}
+
+	pmbus_clear_fault_page(client, -1);
+	return status >= 0;
+}
+
 bool pmbus_check_byte_register(struct i2c_client *client, int page, int reg)
 {
 	return pmbus_check_register(client, _pmbus_read_byte_data, page, reg);
@@ -394,8 +412,7 @@ static struct pmbus_data *pmbus_update_device(struct device *dev)
 
 		for (i = 0; i < info->pages; i++) {
 			data->status[PB_STATUS_BASE + i]
-			    = _pmbus_read_byte_data(client, i,
-						    data->status_register);
+			    = data->read_status(client, i);
 			for (j = 0; j < ARRAY_SIZE(pmbus_status); j++) {
 				struct _pmbus_status *s = &pmbus_status[j];
 
@@ -1051,8 +1068,7 @@ static int pmbus_add_sensor_attrs_one(struct i2c_client *client,
 		 * the generic status register for this page is accessible.
 		 */
 		if (!ret && attr->gbit &&
-		    pmbus_check_byte_register(client, page,
-					      data->status_register)) {
+		    pmbus_check_status_register(client, page)) {
 			ret = pmbus_add_boolean(data, name, "alarm", index,
 						NULL, NULL,
 						PB_STATUS_BASE + page,
@@ -1729,6 +1745,16 @@ static int pmbus_identify_common(struct i2c_client *client,
 	return 0;
 }
 
+static int pmbus_read_status_byte(struct i2c_client *client, int page)
+{
+	return _pmbus_read_byte_data(client, page, PMBUS_STATUS_BYTE);
+}
+
+static int pmbus_read_status_word(struct i2c_client *client, int page)
+{
+	return _pmbus_read_word_data(client, page, PMBUS_STATUS_WORD);
+}
+
 static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
 			     struct pmbus_driver_info *info)
 {
@@ -1736,16 +1762,16 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
 	int page, ret;
 
 	/*
-	 * Some PMBus chips don't support PMBUS_STATUS_BYTE, so try
-	 * to use PMBUS_STATUS_WORD instead if that is the case.
+	 * Some PMBus chips don't support PMBUS_STATUS_WORD, so try
+	 * to use PMBUS_STATUS_BYTE instead if that is the case.
 	 * Bail out if both registers are not supported.
 	 */
-	data->status_register = PMBUS_STATUS_BYTE;
-	ret = i2c_smbus_read_byte_data(client, PMBUS_STATUS_BYTE);
-	if (ret < 0 || ret == 0xff) {
-		data->status_register = PMBUS_STATUS_WORD;
-		ret = i2c_smbus_read_word_data(client, PMBUS_STATUS_WORD);
-		if (ret < 0 || ret == 0xffff) {
+	data->read_status = pmbus_read_status_word;
+	ret = i2c_smbus_read_word_data(client, PMBUS_STATUS_WORD);
+	if (ret < 0 || ret == 0xffff) {
+		data->read_status = pmbus_read_status_byte;
+		ret = i2c_smbus_read_byte_data(client, PMBUS_STATUS_BYTE);
+		if (ret < 0 || ret == 0xff) {
 			dev_err(dev, "PMBus status register not found\n");
 			return -ENODEV;
 		}
-- 
1.8.3.1