linux-kernel - [PATCH RFT 1/2] regulator: pcf50633: Don't write to reserved bits of AUTO output voltage select register

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Message-ID: <1331904943.2891.1.camel@phoenix>
Date:	Fri, 16 Mar 2012 21:35:43 +0800
From:	Axel Lin <axel.lin@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	Balaji Rao <balajirrao@...nmoko.org>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Liam Girdwood <lrg@...com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Subject: [PATCH RFT 1/2] regulator: pcf50633: Don't write to reserved bits
 of AUTO output voltage select register

The datasheet says 00000000 to 00101110 are reserved, and the min value of the
voltage setting is 1.8 V.
Thus don't write 0 to AUTO output voltage select register (address 1Ah).

Table 50. AUTOOUT - AUTO output voltage select register (address 1Ah) bit description[1]
Bit Symbol Access Description
7:0 auto_out R/W VO(prog) = 0.625 + auto_out × 0.025 V
eg. 00000000 to 00101110: reserved
00101111: 1.8 V (min)
01010011: 2.7 V
01101010: 3.275 V
01101011: 3.300 V
01101100: 3.325 V
01111111 : 3.800 V (max)
..... .....
11111110 : 3.800 V
11111111 : 3.800 V

This patch also fixes a bug in pcf50633_regulator_list_voltage.
It is wrong to do "index += 0x2f" for PCF50633_REGULATOR_AUTO in
pcf50633_regulator_list_voltage. The purpose of adding 0x2f to index is because
current code return 0 in auto_voltage_bits when millivolts < 1800.
For millivolts > 1800, adding 0x2f to index is wrong.

We should handle this by
return -EINVAL if the selector is in the reserved range of AUTOOUT.

Signed-off-by: Axel Lin <axel.lin@...il.com>
---
 drivers/regulator/pcf50633-regulator.c |   23 +++++------------------
 1 files changed, 5 insertions(+), 18 deletions(-)

diff --git a/drivers/regulator/pcf50633-regulator.c b/drivers/regulator/pcf50633-regulator.c
index 6db46c6..3cefc63 100644
--- a/drivers/regulator/pcf50633-regulator.c
+++ b/drivers/regulator/pcf50633-regulator.c
@@ -52,7 +52,7 @@ static const u8 pcf50633_regulator_registers[PCF50633_NUM_REGULATORS] = {
 static u8 auto_voltage_bits(unsigned int millivolts)
 {
 	if (millivolts < 1800)
-		return 0;
+		return 0x2f;
 	if (millivolts > 3800)
 		return 0xff;
 
@@ -87,9 +87,6 @@ static u8 ldo_voltage_bits(unsigned int millivolts)
 /* Obtain voltage value from bits */
 static unsigned int auto_voltage_value(u8 bits)
 {
-	if (bits < 0x2f)
-		return 0;
-
 	return 625 + (bits * 25);
 }
 
@@ -161,6 +158,9 @@ static int pcf50633_regulator_voltage_value(enum pcf50633_regulator_id id,
 
 	switch (id) {
 	case PCF50633_REGULATOR_AUTO:
+		/* AUTOOUT: 00000000 to 00101110 are reserved */
+		if (bits < 0x2f)
+			return -EINVAL;
 		millivolts = auto_voltage_value(bits);
 		break;
 	case PCF50633_REGULATOR_DOWN1:
@@ -208,20 +208,7 @@ static int pcf50633_regulator_get_voltage(struct regulator_dev *rdev)
 static int pcf50633_regulator_list_voltage(struct regulator_dev *rdev,
 						unsigned int index)
 {
-	struct pcf50633 *pcf;
-	int regulator_id;
-
-	pcf = rdev_get_drvdata(rdev);
-
-	regulator_id = rdev_get_id(rdev);
-
-	switch (regulator_id) {
-	case PCF50633_REGULATOR_AUTO:
-		index += 0x2f;
-		break;
-	default:
-		break;
-	}
+	int regulator_id = rdev_get_id(rdev);
 
 	return pcf50633_regulator_voltage_value(regulator_id, index);
 }
-- 
1.7.5.4



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