From 022dcdf083d67db34f5237369d3501ca5708d8eb Mon Sep 17 00:00:00 2001
From: Axel Lin <axel.lin@gmail.com>
Date: Mon, 19 Mar 2012 10:55:24 +0800
Subject: [PATCH] regulator: pcf50633: Don't write to reserved bits of AUTO
 output voltage select register
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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:
In regulator core _regulator_do_set_voltage function:

        if (rdev->desc->ops->set_voltage) {
                ret = rdev->desc->ops->set_voltage(rdev, min_uV, max_uV,
                                                   &selector);

                if (rdev->desc->ops->list_voltage)
                        selector = rdev->desc->ops->list_voltage(rdev,
                                                                 selector);
                else
                        selector = -1;

The list_voltage call here takes the selector got from set_voltage callback.
Thus adding 0x2f to the index in pcf50633_regulator_list_voltage looks wrong to me.

e.g.
If min_uV < 1.8V, pcf50633_regulator_set_voltage sets 0 to selector.
For this case, adding 0x2f to the index in pcf50633_regulator_list_voltage is correct.
However, if min_uV == 1.8V, pcf50633_regulator_set_voltage sets 0x2f to selector.
Adding 0x2f to the index in pcf50633_regulator_list_voltage in this case is wrong.

What this patch does is:
The minimal voltage setting for AUTOOUT is 0x2f.
Thus for the case min_uV < 1.8, set the voltage setting to 1.8V by writting
0x2f to AUTOOUT register and set selector = 0x2f.
So we don't write the rserved range to AUTOOUT register.
Which means the possible range of AUTOOUT register value is 0x2f ~ 0xff.

We have no problem in regulator_get_voltage.
Since we won't write 0~0x2e to AUTOOUT register, we have no problem converting
the bits we read to voltage. The equation in auto_voltage_value works fine.

For list_voltage, we need to take into account the case selector is 0 ~ 0x2e
because the regulator core assumes the selector is starting from 0.
This patch returns 0 for the cases selector is 0 ~ 0x2e, which means
"this selector code can't be used on this system".

The regulator core iterates from 0 to n_voltages to find the small voltage
in the specific range. The n_voltages settings for AUTOOUT should be 128 now,
including the reserved range of AUTOOUT.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
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