diff options
Diffstat (limited to 'drivers/mfd/max14577.c')
| -rw-r--r-- | drivers/mfd/max14577.c | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/drivers/mfd/max14577.c b/drivers/mfd/max14577.c index 6599407b5624..b8af263be594 100644 --- a/drivers/mfd/max14577.c +++ b/drivers/mfd/max14577.c @@ -26,6 +26,87 @@ #include <linux/mfd/max14577.h> #include <linux/mfd/max14577-private.h> +/* + * Table of valid charger currents for different Maxim chipsets. + * It is placed here because it is used by both charger and regulator driver. + */ +const struct maxim_charger_current maxim_charger_currents[] = { + [MAXIM_DEVICE_TYPE_UNKNOWN] = { 0, 0, 0, 0 }, + [MAXIM_DEVICE_TYPE_MAX14577] = { + .min = MAX14577_CHARGER_CURRENT_LIMIT_MIN, + .high_start = MAX14577_CHARGER_CURRENT_LIMIT_HIGH_START, + .high_step = MAX14577_CHARGER_CURRENT_LIMIT_HIGH_STEP, + .max = MAX14577_CHARGER_CURRENT_LIMIT_MAX, + }, + [MAXIM_DEVICE_TYPE_MAX77836] = { + .min = MAX77836_CHARGER_CURRENT_LIMIT_MIN, + .high_start = MAX77836_CHARGER_CURRENT_LIMIT_HIGH_START, + .high_step = MAX77836_CHARGER_CURRENT_LIMIT_HIGH_STEP, + .max = MAX77836_CHARGER_CURRENT_LIMIT_MAX, + }, +}; +EXPORT_SYMBOL_GPL(maxim_charger_currents); + +/* + * maxim_charger_calc_reg_current - Calculate register value for current + * @limits: constraints for charger, matching the MBCICHWRC register + * @min_ua: minimal requested current, micro Amps + * @max_ua: maximum requested current, micro Amps + * @dst: destination to store calculated register value + * + * Calculates the value of MBCICHWRC (Fast Battery Charge Current) register + * for given current and stores it under pointed 'dst'. The stored value + * combines low bit (MBCICHWRCL) and high bits (MBCICHWRCH). It is also + * properly shifted. + * + * The calculated register value matches the current which: + * - is always between <limits.min, limits.max>; + * - is always less or equal to max_ua; + * - is the highest possible value; + * - may be lower than min_ua. + * + * On success returns 0. On error returns -EINVAL (requested min/max current + * is outside of given charger limits) and 'dst' is not set. + */ +int maxim_charger_calc_reg_current(const struct maxim_charger_current *limits, + unsigned int min_ua, unsigned int max_ua, u8 *dst) +{ + unsigned int current_bits = 0xf; + + if (min_ua > max_ua) + return -EINVAL; + + if (min_ua > limits->max || max_ua < limits->min) + return -EINVAL; + + if (max_ua < limits->high_start) { + /* + * Less than high_start, so set the minimal current + * (turn Low Bit off, 0 as high bits). + */ + *dst = 0x0; + return 0; + } + + /* max_ua is in range: <high_start, infinite>, cut it to limits.max */ + max_ua = min(limits->max, max_ua); + max_ua -= limits->high_start; + /* + * There is no risk of overflow 'max_ua' here because: + * - max_ua >= limits.high_start + * - BUILD_BUG checks that 'limits' are: max >= high_start + high_step + */ + current_bits = max_ua / limits->high_step; + + /* Turn Low Bit on (use range <limits.high_start, limits.max>) ... */ + *dst = 0x1 << CHGCTRL4_MBCICHWRCL_SHIFT; + /* and set proper High Bits */ + *dst |= current_bits << CHGCTRL4_MBCICHWRCH_SHIFT; + + return 0; +} +EXPORT_SYMBOL_GPL(maxim_charger_calc_reg_current); + static const struct mfd_cell max14577_devs[] = { { .name = "max14577-muic", @@ -466,6 +547,20 @@ static int __init max14577_i2c_init(void) BUILD_BUG_ON(ARRAY_SIZE(max14577_i2c_id) != MAXIM_DEVICE_TYPE_NUM); BUILD_BUG_ON(ARRAY_SIZE(max14577_dt_match) != MAXIM_DEVICE_TYPE_NUM); + /* Valid charger current values must be provided for each chipset */ + BUILD_BUG_ON(ARRAY_SIZE(maxim_charger_currents) != MAXIM_DEVICE_TYPE_NUM); + + /* Check for valid values for charger */ + BUILD_BUG_ON(MAX14577_CHARGER_CURRENT_LIMIT_HIGH_START + + MAX14577_CHARGER_CURRENT_LIMIT_HIGH_STEP * 0xf != + MAX14577_CHARGER_CURRENT_LIMIT_MAX); + BUILD_BUG_ON(MAX14577_CHARGER_CURRENT_LIMIT_HIGH_STEP == 0); + + BUILD_BUG_ON(MAX77836_CHARGER_CURRENT_LIMIT_HIGH_START + + MAX77836_CHARGER_CURRENT_LIMIT_HIGH_STEP * 0xf != + MAX77836_CHARGER_CURRENT_LIMIT_MAX); + BUILD_BUG_ON(MAX77836_CHARGER_CURRENT_LIMIT_HIGH_STEP == 0); + return i2c_add_driver(&max14577_i2c_driver); } subsys_initcall(max14577_i2c_init); |