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hwmon: epm_adc: Add psoc voltage scaling

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For voltage channels the psoc uses a 12 bit ADC. For current
channels a 16 bit ADC is used with the sign bit. Use the
channel mask to determine the channel scaling being performed
is for a voltage channel and scale the result appropriately
for voltage and current channel.

Change-Id: I7e238dd6ed0de6bcfaaf4186eaa3770de43d254f
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>
This commit is contained in:
Siddartha Mohanadoss 2012-12-12 10:36:07 -08:00 committed by Stephen Boyd
parent 4d46b40b02
commit 85cd4b4412
1 changed files with 16 additions and 5 deletions
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21
drivers/hwmon/epm_adc.c
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@ -95,7 +95,8 @@
#define EPM_PSOC_GLOBAL_ENABLE 81
#define EPM_PSOC_VREF_VOLTAGE 2048
#define EPM_PSOC_MAX_ADC_CODE_16_BIT 32767
#define EPM_PSOC_MAX_ADC_CODE_15_BIT 32767
#define EPM_PSOC_MAX_ADC_CODE_12_BIT 4096
#define EPM_GLOBAL_ENABLE_MIN_DELAY 5000
#define EPM_GLOBAL_ENABLE_MAX_DELAY 5100
@ -590,13 +591,23 @@ static int epm_psoc_scale_result(uint32_t result, uint32_t index)
struct epm_adc_drv *epm_adc = epm_adc_drv;
int32_t result_cur;
/* result = 2.048V/(32767 * gain * rsense) */
result_cur = (((EPM_PSOC_VREF_VOLTAGE * result)/
EPM_PSOC_MAX_ADC_CODE_16_BIT) * 1000);
if ((1 << index) & epm_adc->channel_mask) {
/* result = (2.048V * code)/(4096 * gain * rsense) */
result_cur = ((EPM_PSOC_VREF_VOLTAGE * result)/
EPM_PSOC_MAX_ADC_CODE_12_BIT);
result_cur = (result_cur/
result_cur = (result_cur/
(epm_adc->epm_psoc_ch_prop[index].gain *
epm_adc->epm_psoc_ch_prop[index].resistorvalue));
} else {
/* result = (2.048V * code)/(32767 * gain * rsense) */
result_cur = (((EPM_PSOC_VREF_VOLTAGE * result)/
EPM_PSOC_MAX_ADC_CODE_15_BIT) * 1000);
result_cur = (result_cur/
(epm_adc->epm_psoc_ch_prop[index].gain *
epm_adc->epm_psoc_ch_prop[index].resistorvalue));
}
return result_cur;
}