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ab8500_charger: Charger current step-up/down
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There is no state machine in the AB to step up/down the charger
current to avoid dips and spikes on VBUS and VBAT when charging
is started. Instead this is implemented in SW.

Signed-off-by: Johan Bjornstedt <johan.bjornstedt@stericsson.com>
Signed-off-by: Mattias Wallin <mattias.wallin@stericsson.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Karl KOMIEROWSKI <karl.komierowski@stericsson.com>
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Johan Bjornstedt authored and Lee Jones committed Dec 11, 2012
1 parent f5695a3 commit f8e96df
Showing 1 changed file with 135 additions and 40 deletions.
175 changes: 135 additions & 40 deletions drivers/power/ab8500_charger.c
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Original file line number Diff line number Diff line change
Expand Up @@ -79,6 +79,9 @@
/* Lowest charger voltage is 3.39V -> 0x4E */
#define LOW_VOLT_REG 0x4E

/* Step up/down delay in us */
#define STEP_UDELAY 1000

/* UsbLineStatus register - usb types */
enum ab8500_charger_link_status {
USB_STAT_NOT_CONFIGURED,
Expand Down Expand Up @@ -935,6 +938,88 @@ static int ab8500_charger_get_usb_cur(struct ab8500_charger *di)
return 0;
}

/**
* ab8500_charger_set_current() - set charger current
* @di: pointer to the ab8500_charger structure
* @ich: charger current, in mA
* @reg: select what charger register to set
*
* Set charger current.
* There is no state machine in the AB to step up/down the charger
* current to avoid dips and spikes on MAIN, VBUS and VBAT when
* charging is started. Instead we need to implement
* this charger current step-up/down here.
* Returns error code in case of failure else 0(on success)
*/
static int ab8500_charger_set_current(struct ab8500_charger *di,
int ich, int reg)
{
int ret, i;
int curr_index, prev_curr_index, shift_value;
u8 reg_value;

switch (reg) {
case AB8500_MCH_IPT_CURLVL_REG:
shift_value = MAIN_CH_INPUT_CURR_SHIFT;
curr_index = ab8500_current_to_regval(ich);
break;
case AB8500_USBCH_IPT_CRNTLVL_REG:
shift_value = VBUS_IN_CURR_LIM_SHIFT;
curr_index = ab8500_vbus_in_curr_to_regval(ich);
break;
case AB8500_CH_OPT_CRNTLVL_REG:
shift_value = 0;
curr_index = ab8500_current_to_regval(ich);
break;
default:
dev_err(di->dev, "%s current register not valid\n", __func__);
return -ENXIO;
}

if (curr_index < 0) {
dev_err(di->dev, "requested current limit out-of-range\n");
return -ENXIO;
}

ret = abx500_get_register_interruptible(di->dev, AB8500_CHARGER,
reg, &reg_value);
if (ret < 0) {
dev_err(di->dev, "%s read failed\n", __func__);
return ret;
}
prev_curr_index = (reg_value >> shift_value);

/* only update current if it's been changed */
if (prev_curr_index == curr_index)
return 0;

dev_dbg(di->dev, "%s set charger current: %d mA for reg: 0x%02x\n",
__func__, ich, reg);

if (prev_curr_index > curr_index) {
for (i = prev_curr_index - 1; i >= curr_index; i--) {
ret = abx500_set_register_interruptible(di->dev,
AB8500_CHARGER, reg, (u8) i << shift_value);
if (ret) {
dev_err(di->dev, "%s write failed\n", __func__);
return ret;
}
usleep_range(STEP_UDELAY, STEP_UDELAY * 2);
}
} else {
for (i = prev_curr_index + 1; i <= curr_index; i++) {
ret = abx500_set_register_interruptible(di->dev,
AB8500_CHARGER, reg, (u8) i << shift_value);
if (ret) {
dev_err(di->dev, "%s write failed\n", __func__);
return ret;
}
usleep_range(STEP_UDELAY, STEP_UDELAY * 2);
}
}
return ret;
}

/**
* ab8500_charger_set_vbus_in_curr() - set VBUS input current limit
* @di: pointer to the ab8500_charger structure
Expand All @@ -946,8 +1031,6 @@ static int ab8500_charger_get_usb_cur(struct ab8500_charger *di)
static int ab8500_charger_set_vbus_in_curr(struct ab8500_charger *di,
int ich_in)
{
int ret;
int input_curr_index;
int min_value;

/* We should always use to lowest current limit */
Expand All @@ -966,19 +1049,38 @@ static int ab8500_charger_set_vbus_in_curr(struct ab8500_charger *di,
break;
}

input_curr_index = ab8500_vbus_in_curr_to_regval(min_value);
if (input_curr_index < 0) {
dev_err(di->dev, "VBUS input current limit too high\n");
return -ENXIO;
}
return ab8500_charger_set_current(di, min_value,
AB8500_USBCH_IPT_CRNTLVL_REG);
}

ret = abx500_set_register_interruptible(di->dev, AB8500_CHARGER,
AB8500_USBCH_IPT_CRNTLVL_REG,
input_curr_index << VBUS_IN_CURR_LIM_SHIFT);
if (ret)
dev_err(di->dev, "%s write failed\n", __func__);
/**
* ab8500_charger_set_main_in_curr() - set main charger input current
* @di: pointer to the ab8500_charger structure
* @ich_in: input charger current, in mA
*
* Set main charger input current.
* Returns error code in case of failure else 0(on success)
*/
static int ab8500_charger_set_main_in_curr(struct ab8500_charger *di,
int ich_in)
{
return ab8500_charger_set_current(di, ich_in,
AB8500_MCH_IPT_CURLVL_REG);
}

return ret;
/**
* ab8500_charger_set_output_curr() - set charger output current
* @di: pointer to the ab8500_charger structure
* @ich_out: output charger current, in mA
*
* Set charger output current.
* Returns error code in case of failure else 0(on success)
*/
static int ab8500_charger_set_output_curr(struct ab8500_charger *di,
int ich_out)
{
return ab8500_charger_set_current(di, ich_out,
AB8500_CH_OPT_CRNTLVL_REG);
}

/**
Expand Down Expand Up @@ -1090,18 +1192,19 @@ static int ab8500_charger_ac_en(struct ux500_charger *charger,
return ret;
}
/* MainChInputCurr: current that can be drawn from the charger*/
ret = abx500_set_register_interruptible(di->dev, AB8500_CHARGER,
AB8500_MCH_IPT_CURLVL_REG,
input_curr_index << MAIN_CH_INPUT_CURR_SHIFT);
ret = ab8500_charger_set_main_in_curr(di,
di->bat->chg_params->ac_curr_max);
if (ret) {
dev_err(di->dev, "%s write failed\n", __func__);
dev_err(di->dev, "%s Failed to set MainChInputCurr\n",
__func__);
return ret;
}
/* ChOutputCurentLevel: protected output current */
ret = abx500_set_register_interruptible(di->dev, AB8500_CHARGER,
AB8500_CH_OPT_CRNTLVL_REG, (u8) curr_index);
ret = ab8500_charger_set_output_curr(di, iset);
if (ret) {
dev_err(di->dev, "%s write failed\n", __func__);
dev_err(di->dev, "%s "
"Failed to set ChOutputCurentLevel\n",
__func__);
return ret;
}

Expand Down Expand Up @@ -1158,12 +1261,11 @@ static int ab8500_charger_ac_en(struct ux500_charger *charger,
return ret;
}

ret = abx500_set_register_interruptible(di->dev,
AB8500_CHARGER,
AB8500_CH_OPT_CRNTLVL_REG, CH_OP_CUR_LVL_0P1);
ret = ab8500_charger_set_output_curr(di, 0);
if (ret) {
dev_err(di->dev,
"%s write failed\n", __func__);
dev_err(di->dev, "%s "
"Failed to set ChOutputCurentLevel\n",
__func__);
return ret;
}
} else {
Expand Down Expand Up @@ -1266,10 +1368,11 @@ static int ab8500_charger_usb_en(struct ux500_charger *charger,
return ret;
}
/* ChOutputCurentLevel: protected output current */
ret = abx500_set_register_interruptible(di->dev, AB8500_CHARGER,
AB8500_CH_OPT_CRNTLVL_REG, (u8) curr_index);
ret = ab8500_charger_set_output_curr(di, ich_out);
if (ret) {
dev_err(di->dev, "%s write failed\n", __func__);
dev_err(di->dev, "%s "
"Failed to set ChOutputCurentLevel\n",
__func__);
return ret;
}
/* Check if VBAT overshoot control should be enabled */
Expand Down Expand Up @@ -1366,7 +1469,6 @@ static int ab8500_charger_update_charger_current(struct ux500_charger *charger,
int ich_out)
{
int ret;
int curr_index;
struct ab8500_charger *di;

if (charger->psy.type == POWER_SUPPLY_TYPE_MAINS)
Expand All @@ -1376,18 +1478,11 @@ static int ab8500_charger_update_charger_current(struct ux500_charger *charger,
else
return -ENXIO;

curr_index = ab8500_current_to_regval(ich_out);
if (curr_index < 0) {
dev_err(di->dev,
"Charger current too high, "
"charging not started\n");
return -ENXIO;
}

ret = abx500_set_register_interruptible(di->dev, AB8500_CHARGER,
AB8500_CH_OPT_CRNTLVL_REG, (u8) curr_index);
ret = ab8500_charger_set_output_curr(di, ich_out);
if (ret) {
dev_err(di->dev, "%s write failed\n", __func__);
dev_err(di->dev, "%s "
"Failed to set ChOutputCurentLevel\n",
__func__);
return ret;
}

Expand Down

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