Re: [PATCH 4/8] power: Add an axp20x-usb-power driver

On Wed, 10 Jun 2015, Hans de Goede wrote:

Hi,

Thanks for the quick review I'll do a v2 addressing your concerns soonish.

On 10-06-15 09:29, Lee Jones wrote:

quoted

On Tue, 09 Jun 2015, Hans de Goede wrote:

quoted

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-ud5FBsm0p/xEiooADzr8i9i2O/JbrIOy@public.gmane.org>
Signed-off-by: Hans de Goede <redacted>
---
 .../bindings/power_supply/axp20x_usb_power.txt     |  34 +++

This needs to be submitted in a seperate patch.

Ok.

quoted

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 drivers/power/Kconfig                              |   7 +
 drivers/power/Makefile                             |   1 +
 drivers/power/axp20x_usb_power.c                   | 241 +++++++++++++++++++++
 include/linux/mfd/axp20x.h                         |  24 ++
 5 files changed, 307 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/power_supply/axp20x_usb_power.txt
 create mode 100644 drivers/power/axp20x_usb_power.c

[...]

quoted

diff --git a/include/linux/mfd/axp20x.h b/include/linux/mfd/axp20x.h
index f4290ae..d7adb2e 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 {
 	AXP202_ID = 0,
 	AXP209_ID,

@@ -366,4 +368,26 @@ struct axp20x_fg_pdata {
 	int thermistor_curve[MAX_THERM_CURVE_SIZE][2];
 };

+/* generic helper function for reading 9-16 bit wide regs */
+static inline int axp20x_read_16bit(struct regmap *regmap,

This is only used twice and only in one file.

Do you know of any other uses of this call that will be upstreamed
shortly?

Yes I plan to write drivers for the other 3 power_supply class
cells (ac-power, battery-charger, rtc-bat-charger) in the axp209,
and most of those need the same helper which I why I put it here.

Okay.

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+				    unsigned int reg, unsigned int width)

The function name is a bit misleading.

How about: axp20x_read_multibyte_reg ?

axp20x_read_variable_width() ?

quoted

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+{
+	unsigned int v, raw;
+	int r;

'v' and 'r' are not good variable names.

quoted

+	r = regmap_read(regmap, reg, &v);
+	if (r)
+		return r;
+
+	raw = v << (width - 8);

So 'reg' is expected to be top end loaded?

E.g A value of say 0x0101 (257) in 9 bits will look like this:

reg          reg + 1
1000 0000b   0000 0001b

Yes, I guess this was done so that you can get all the 8 msb-s
in a single read if you do not care about the lsb-s.

Odd, but okay.

quoted

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+	r = regmap_read(regmap, reg + 1, &v);
+	if (r)
+		return r;
+
+	raw |= v;
+
+	return raw;
+}
+
 #endif /* __LINUX_MFD_AXP20X_H */

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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