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 fa02f20b79ff..e9beeda4cbe5 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);