hwmon: (ads1015) Make gain and datarate configurable

Configuration for ads1015 gain and datarate is possible via
devicetree or platform data.

This is a followup patch to previous ads1015 patches on Jean Delvares
tree.

Signed-off-by: Dirk Eibach <eibach@gdsys.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 109 insertions, 40 deletions

diff --git a/drivers/hwmon/ads1015.c b/drivers/hwmon/ads1015.c
index fa02f20..e9beeda 100644
--- a/drivers/hwmon/ads1015.c
+++ b/drivers/hwmon/ads1015.c
@@ -45,12 +45,18 @@ enum {
 static const unsigned int fullscale_table[8] = {
 	6144, 4096, 2048, 1024, 512, 256, 256, 256 };
 
-#define ADS1015_CONFIG_CHANNELS 8
+/* Data rates in samples per second */
+static const unsigned int data_rate_table[8] = {
+	128, 250, 490, 920, 1600, 2400, 3300, 3300 };
+
 #define ADS1015_DEFAULT_CHANNELS 0xff
+#define ADS1015_DEFAULT_PGA 2
+#define ADS1015_DEFAULT_DATA_RATE 4
 
 struct ads1015_data {
 	struct device *hwmon_dev;
 	struct mutex update_lock; /* mutex protect updates */
+	struct ads1015_channel_data channel_data[ADS1015_CHANNELS];
 };
 
 static s32 ads1015_read_reg(struct i2c_client *client, unsigned int reg)
@@ -71,40 +77,42 @@ static int ads1015_read_value(struct i2c_client *client, unsigned int channel,
 {
 	u16 config;
 	s16 conversion;
-	unsigned int pga;
-	int fullscale;
-	unsigned int k;
 	struct ads1015_data *data = i2c_get_clientdata(client);
+	unsigned int pga = data->channel_data[channel].pga;
+	int fullscale;
+	unsigned int data_rate = data->channel_data[channel].data_rate;
+	unsigned int conversion_time_ms;
 	int res;
 
 	mutex_lock(&data->update_lock);
 
-	/* get fullscale voltage */
+	/* get channel parameters */
 	res = ads1015_read_reg(client, ADS1015_CONFIG);
 	if (res < 0)
 		goto err_unlock;
 	config = res;
-	pga = (config >> 9) & 0x0007;
 	fullscale = fullscale_table[pga];
+	conversion_time_ms = DIV_ROUND_UP(1000, data_rate_table[data_rate]);
 
-	/* set channel and start single conversion */
-	config &= ~(0x0007 << 12);
-	config |= (1 << 15) | (1 << 8) | (channel & 0x0007) << 12;
+	/* setup and start single conversion */
+	config &= 0x001f;
+	config |= (1 << 15) | (1 << 8);
+	config |= (channel & 0x0007) << 12;
+	config |= (pga & 0x0007) << 9;
+	config |= (data_rate & 0x0007) << 5;
 
-	/* wait until conversion finished */
 	res = ads1015_write_reg(client, ADS1015_CONFIG, config);
 	if (res < 0)
 		goto err_unlock;
-	for (k = 0; k < 5; ++k) {
-		msleep(1);
-		res = ads1015_read_reg(client, ADS1015_CONFIG);
-		if (res < 0)
-			goto err_unlock;
-		config = res;
-		if (config & (1 << 15))
-			break;
-	}
-	if (k == 5) {
+
+	/* wait until conversion finished */
+	msleep(conversion_time_ms);
+	res = ads1015_read_reg(client, ADS1015_CONFIG);
+	if (res < 0)
+		goto err_unlock;
+	config = res;
+	if (!(config & (1 << 15))) {
+		/* conversion not finished in time */
 		res = -EIO;
 		goto err_unlock;
 	}
@@ -160,35 +168,97 @@ static int ads1015_remove(struct i2c_client *client)
 	int k;
 
 	hwmon_device_unregister(data->hwmon_dev);
-	for (k = 0; k < ADS1015_CONFIG_CHANNELS; ++k)
+	for (k = 0; k < ADS1015_CHANNELS; ++k)
 		device_remove_file(&client->dev, &ads1015_in[k].dev_attr);
 	kfree(data);
 	return 0;
 }
 
-static unsigned int ads1015_get_exported_channels(struct i2c_client *client)
-{
-	struct ads1015_platform_data *pdata = dev_get_platdata(&client->dev);
 #ifdef CONFIG_OF
-	struct device_node *np = client->dev.of_node;
-	const __be32 *of_channels;
-	int of_channels_size;
+static int ads1015_get_channels_config_of(struct i2c_client *client)
+{
+	struct ads1015_data *data = i2c_get_clientdata(client);
+	struct device_node *node;
+
+	if (!client->dev.of_node
+	    || !of_get_next_child(client->dev.of_node, NULL))
+		return -EINVAL;
+
+	for_each_child_of_node(client->dev.of_node, node) {
+		const __be32 *property;
+		int len;
+		unsigned int channel;
+		unsigned int pga = ADS1015_DEFAULT_PGA;
+		unsigned int data_rate = ADS1015_DEFAULT_DATA_RATE;
+
+		property = of_get_property(node, "reg", &len);
+		if (!property || len != sizeof(int)) {
+			dev_err(&client->dev, "invalid reg on %s\n",
+				node->full_name);
+			continue;
+		}
+
+		channel = be32_to_cpup(property);
+		if (channel > ADS1015_CHANNELS) {
+			dev_err(&client->dev,
+				"invalid channel index %d on %s\n",
+				channel, node->full_name);
+			continue;
+		}
+
+		property = of_get_property(node, "ti,gain", &len);
+		if (property && len == sizeof(int)) {
+			pga = be32_to_cpup(property);
+			if (pga > 6) {
+				dev_err(&client->dev,
+					"invalid gain on %s\n",
+					node->full_name);
+			}
+		}
+
+		property = of_get_property(node, "ti,datarate", &len);
+		if (property && len == sizeof(int)) {
+			data_rate = be32_to_cpup(property);
+			if (data_rate > 7) {
+				dev_err(&client->dev,
+					"invalid data_rate on %s\n",
+					node->full_name);
+			}
+		}
+
+		data->channel_data[channel].enabled = true;
+		data->channel_data[channel].pga = pga;
+		data->channel_data[channel].data_rate = data_rate;
+	}
+
+	return 0;
+}
 #endif
 
+static void ads1015_get_channels_config(struct i2c_client *client)
+{
+	unsigned int k;
+	struct ads1015_data *data = i2c_get_clientdata(client);
+	struct ads1015_platform_data *pdata = dev_get_platdata(&client->dev);
+
 	/* prefer platform data */
-	if (pdata)
-		return pdata->exported_channels;
+	if (pdata) {
+		memcpy(data->channel_data, pdata->channel_data,
+		       sizeof(data->channel_data));
+		return;
+	}
 
 #ifdef CONFIG_OF
-	/* fallback on OF */
-	of_channels = of_get_property(np, "exported-channels",
-				      &of_channels_size);
-	if (of_channels && (of_channels_size == sizeof(*of_channels)))
-		return be32_to_cpup(of_channels);
+	if (!ads1015_get_channels_config_of(client))
+		return;
 #endif
 
 	/* fallback on default configuration */
-	return ADS1015_DEFAULT_CHANNELS;
+	for (k = 0; k < ADS1015_CHANNELS; ++k) {
+		data->channel_data[k].enabled = true;
+		data->channel_data[k].pga = ADS1015_DEFAULT_PGA;
+		data->channel_data[k].data_rate = ADS1015_DEFAULT_DATA_RATE;
+	}
 }
 
 static int ads1015_probe(struct i2c_client *client,
@@ -196,7 +266,6 @@ static int ads1015_probe(struct i2c_client *client,
 {
 	struct ads1015_data *data;
 	int err;
-	unsigned int exported_channels;
 	unsigned int k;
 
 	data = kzalloc(sizeof(struct ads1015_data), GFP_KERNEL);
@@ -209,9 +278,9 @@ static int ads1015_probe(struct i2c_client *client,
 	mutex_init(&data->update_lock);
 
 	/* build sysfs attribute group */
-	exported_channels = ads1015_get_exported_channels(client);
-	for (k = 0; k < ADS1015_CONFIG_CHANNELS; ++k) {
-		if (!(exported_channels & (1<<k)))
+	ads1015_get_channels_config(client);
+	for (k = 0; k < ADS1015_CHANNELS; ++k) {
+		if (!data->channel_data[k].enabled)
 			continue;
 		err = device_create_file(&client->dev, &ads1015_in[k].dev_attr);
 		if (err)
@@ -227,7 +296,7 @@ static int ads1015_probe(struct i2c_client *client,
 	return 0;
 
 exit_remove:
-	for (k = 0; k < ADS1015_CONFIG_CHANNELS; ++k)
+	for (k = 0; k < ADS1015_CHANNELS; ++k)
 		device_remove_file(&client->dev, &ads1015_in[k].dev_attr);
 exit_free:
 	kfree(data);