mfd: Add AUXADC support for WM8350

The auxiliary ADC in the WM8350 is shared between several subdevices
so access to it needs to be arbitrated by the core driver.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@openedhand.com>

3 files changed, 60 insertions, 1 deletions

diff --git a/drivers/mfd/wm8350-core.c b/drivers/mfd/wm8350-core.c
index c013afde260d..60439bd3984d 100644
--- a/drivers/mfd/wm8350-core.c
+++ b/drivers/mfd/wm8350-core.c
@@ -63,7 +63,6 @@
  */
 static DEFINE_MUTEX(io_mutex);
 static DEFINE_MUTEX(reg_lock_mutex);
-static DEFINE_MUTEX(auxadc_mutex);
 
 /* Perform a physical read from the device.
  */
@@ -1082,6 +1081,55 @@ int wm8350_unmask_irq(struct wm8350 *wm8350, int irq)
 }
 EXPORT_SYMBOL_GPL(wm8350_unmask_irq);
 
+int wm8350_read_auxadc(struct wm8350 *wm8350, int channel, int scale, int vref)
+{
+        u16 reg, result = 0;
+        int tries = 5;
+
+        if (channel < WM8350_AUXADC_AUX1 || channel > WM8350_AUXADC_TEMP)
+                return -EINVAL;
+        if (channel >= WM8350_AUXADC_USB && channel <= WM8350_AUXADC_TEMP
+            && (scale != 0 || vref != 0))
+                return -EINVAL;
+
+        mutex_lock(&wm8350->auxadc_mutex);
+
+        /* Turn on the ADC */
+        reg = wm8350_reg_read(wm8350, WM8350_POWER_MGMT_5);
+        wm8350_reg_write(wm8350, WM8350_POWER_MGMT_5, reg | WM8350_AUXADC_ENA);
+
+        if (scale || vref) {
+                reg = scale << 13;
+                reg |= vref << 12;
+                wm8350_reg_write(wm8350, WM8350_AUX1_READBACK + channel, reg);
+        }
+
+        reg = wm8350_reg_read(wm8350, WM8350_DIGITISER_CONTROL_1);
+        reg |= 1 << channel | WM8350_AUXADC_POLL;
+        wm8350_reg_write(wm8350, WM8350_DIGITISER_CONTROL_1, reg);
+
+        do {
+                schedule_timeout_interruptible(1);
+                reg = wm8350_reg_read(wm8350, WM8350_DIGITISER_CONTROL_1);
+        } while (tries-- && (reg & WM8350_AUXADC_POLL));
+
+        if (!tries)
+                dev_err(wm8350->dev, "adc chn %d read timeout\n", channel);
+        else
+                result = wm8350_reg_read(wm8350,
+                                         WM8350_AUX1_READBACK + channel);
+
+        /* Turn off the ADC */
+        reg = wm8350_reg_read(wm8350, WM8350_POWER_MGMT_5);
+        wm8350_reg_write(wm8350, WM8350_POWER_MGMT_5,
+                         reg & ~WM8350_AUXADC_ENA);
+
+        mutex_unlock(&wm8350->auxadc_mutex);
+
+        return result & WM8350_AUXADC_DATA1_MASK;
+}
+EXPORT_SYMBOL_GPL(wm8350_read_auxadc);
+
 /*
  * Cache is always host endian.
  */
@@ -1239,6 +1287,7 @@ int wm8350_device_init(struct wm8350 *wm8350, int irq,
                 }
         }
 
+        mutex_init(&wm8350->auxadc_mutex);
         mutex_init(&wm8350->irq_mutex);
         INIT_WORK(&wm8350->irq_work, wm8350_irq_worker);
         if (irq) {
diff --git a/include/linux/mfd/wm8350/comparator.h b/include/linux/mfd/wm8350/comparator.h
index 053788649452..54bc5d0fd502 100644
--- a/include/linux/mfd/wm8350/comparator.h
+++ b/include/linux/mfd/wm8350/comparator.h
@@ -164,4 +164,12 @@
 #define WM8350_AUXADC_BATT                      6
 #define WM8350_AUXADC_TEMP                      7
 
+struct wm8350;
+
+/*
+ * AUX ADC Readback
+ */
+int wm8350_read_auxadc(struct wm8350 *wm8350, int channel, int scale,
+                       int vref);
+
 #endif
diff --git a/include/linux/mfd/wm8350/core.h b/include/linux/mfd/wm8350/core.h
index 9490ec175d5a..cc190055b9c4 100644
--- a/include/linux/mfd/wm8350/core.h
+++ b/include/linux/mfd/wm8350/core.h
@@ -573,6 +573,8 @@ struct wm8350 {
                          void *src);
         u16 *reg_cache;
 
+        struct mutex auxadc_mutex;
+
         /* Interrupt handling */
         struct work_struct irq_work;
         struct mutex irq_mutex; /* IRQ table mutex */