power: Add an axp20x-usb-power driver

This adds a driver for the usb power_supply bits of the axp20x PMICs.

I initially started writing my own driver, before coming aware of
Bruno Prémont's excellent earlier RFC with a driver for this.

My driver was lacking CURRENT_MAX and VOLTAGE_MIN support Bruno's
drvier has, so I've copied the code for those from his driver.

Note that the AC-power-supply and battery charger bits will need separate
drivers. Each one needs its own devictree child-node so that other
devicetree nodes can reference the right power-supply, and thus each one
will get its own mfd-cell / platform_device and platform-driver.

Cc: Bruno Prémont <bonbons@linux-vserver.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/include/linux/mfd/axp20x.h b/include/linux/mfd/axp20x.h
index cc8ad1e1a307..b24c771cebd5 100644
--- a/include/linux/mfd/axp20x.h
+++ b/include/linux/mfd/axp20x.h
@@ -11,6 +11,8 @@
 #ifndef __LINUX_MFD_AXP20X_H
 #define __LINUX_MFD_AXP20X_H
 
+#include <linux/regmap.h>
+
 enum {
 	AXP152_ID = 0,
 	AXP202_ID,
@@ -438,4 +440,26 @@ struct axp288_extcon_pdata {
 	struct gpio_desc *gpio_mux_cntl;
 };
 
+/* generic helper function for reading 9-16 bit wide regs */
+static inline int axp20x_read_variable_width(struct regmap *regmap,
+	unsigned int reg, unsigned int width)
+{
+	unsigned int reg_val, result;
+	int err;
+
+	err = regmap_read(regmap, reg, &reg_val);
+	if (err)
+		return err;
+
+	result = reg_val << (width - 8);
+
+	err = regmap_read(regmap, reg + 1, &reg_val);
+	if (err)
+		return err;
+
+	result |= reg_val;
+
+	return result;
+}
+
 #endif /* __LINUX_MFD_AXP20X_H */