diff options
Diffstat (limited to 'drivers/regulator/bd718x7-regulator.c')
| -rw-r--r-- | drivers/regulator/bd718x7-regulator.c | 164 |
1 files changed, 157 insertions, 7 deletions
diff --git a/drivers/regulator/bd718x7-regulator.c b/drivers/regulator/bd718x7-regulator.c index 0774467994fb..e6d5d98c3cea 100644 --- a/drivers/regulator/bd718x7-regulator.c +++ b/drivers/regulator/bd718x7-regulator.c @@ -1323,13 +1323,142 @@ static void mark_hw_controlled(struct device *dev, struct device_node *np, dev_warn(dev, "Bad regulator node\n"); } -static int get_hw_controlled_regulators(struct device *dev, - struct bd718xx_regulator_data *reg_data, - unsigned int num_reg_data, int *info) +/* + * Setups where regulator (especially the buck8) output voltage is scaled + * by adding external connection where some other regulator output is connected + * to feedback-pin (over suitable resistors) is getting popular amongst users + * of BD71837. (This allows for example scaling down the buck8 voltages to suit + * lover GPU voltages for projects where buck8 is (ab)used to supply power + * for GPU. Additionally some setups do allow DVS for buck8 but as this do + * produce voltage spikes the HW must be evaluated to be able to survive this + * - hence I keep the DVS disabled for non DVS bucks by default. I don't want + * to help you burn your proto board) + * + * So we allow describing this external connection from DT and scale the + * voltages accordingly. This is what the connection should look like: + * + * |------------| + * | buck 8 |-------+----->Vout + * | | | + * |------------| | + * | FB pin | + * | | + * +-------+--R2---+ + * | + * R1 + * | + * V FB-pull-up + * + * Here the buck output is sifted according to formula: + * + * Vout_o = Vo - (Vpu - Vo)*R2/R1 + * Linear_step = step_orig*(R1+R2)/R1 + * + * where: + * Vout_o is adjusted voltage output at vsel reg value 0 + * Vo is original voltage output at vsel reg value 0 + * Vpu is the pull-up voltage V FB-pull-up in the picture + * R1 and R2 are resistor values. + * + * As a real world example for buck8 and a specific GPU: + * VLDO = 1.6V (used as FB-pull-up) + * R1 = 1000ohms + * R2 = 150ohms + * VSEL 0x0 => 0.8V – (VLDO – 0.8) * R2 / R1 = 0.68V + * Linear Step = 10mV * (R1 + R2) / R1 = 11.5mV + */ +static int setup_feedback_loop(struct device *dev, struct device_node *np, + struct bd718xx_regulator_data *reg_data, + unsigned int num_reg_data, int fb_uv) { + int i, r1, r2, ret; + + /* + * We do adjust the values in the global desc based on DT settings. + * This may not be best approach as it can cause problems if more than + * one PMIC is controlled from same processor. I don't see such use-case + * for BD718x7 now - so we spare some bits. + * + * If this will point out to be a problem - then we can allocate new + * bd718xx_regulator_data array at probe and just use the global + * array as a template where we copy initial values. Then we can + * use allocated descs for regultor registration and do IC specific + * modifications to this copy while leaving other PMICs untouched. But + * that means allocating new array for each PMIC - and currently I see + * no need for that. + */ + + for (i = 0; i < num_reg_data; i++) { + struct regulator_desc *desc = ®_data[i].desc; + int j; + + if (!of_node_name_eq(np, desc->of_match)) + continue; + + pr_info("Looking at node '%s'\n", desc->of_match); + + /* The feedback loop connection does not make sense for LDOs */ + if (desc->id >= BD718XX_LDO1) + return -EINVAL; + + ret = of_property_read_u32(np, "rohm,feedback-pull-up-r1-ohms", + &r1); + if (ret) + return ret; + + if (!r1) + return -EINVAL; + + ret = of_property_read_u32(np, "rohm,feedback-pull-up-r2-ohms", + &r2); + if (ret) + return ret; + + if (desc->n_linear_ranges && desc->linear_ranges) { + struct linear_range *new; + + new = devm_kzalloc(dev, desc->n_linear_ranges * + sizeof(struct linear_range), + GFP_KERNEL); + if (!new) + return -ENOMEM; + + for (j = 0; j < desc->n_linear_ranges; j++) { + int min = desc->linear_ranges[j].min; + int step = desc->linear_ranges[j].step; + + min -= (fb_uv - min)*r2/r1; + step = step * (r1 + r2); + step /= r1; + + new[j].min = min; + new[j].step = step; + + dev_dbg(dev, "%s: old range min %d, step %d\n", + desc->name, desc->linear_ranges[j].min, + desc->linear_ranges[j].step); + dev_dbg(dev, "new range min %d, step %d\n", min, + step); + } + desc->linear_ranges = new; + } + dev_dbg(dev, "regulator '%s' has FB pull-up configured\n", + desc->name); + + return 0; + } + + return -ENODEV; +} + +static int get_special_regulators(struct device *dev, + struct bd718xx_regulator_data *reg_data, + unsigned int num_reg_data, int *info) +{ + int ret; struct device_node *np; struct device_node *nproot = dev->of_node; - const char *prop = "rohm,no-regulator-enable-control"; + int uv; *info = 0; @@ -1338,13 +1467,32 @@ static int get_hw_controlled_regulators(struct device *dev, dev_err(dev, "failed to find regulators node\n"); return -ENODEV; } - for_each_child_of_node(nproot, np) - if (of_property_read_bool(np, prop)) + for_each_child_of_node(nproot, np) { + if (of_property_read_bool(np, "rohm,no-regulator-enable-control")) mark_hw_controlled(dev, np, reg_data, num_reg_data, info); + ret = of_property_read_u32(np, "rohm,fb-pull-up-microvolt", + &uv); + if (ret) { + if (ret == -EINVAL) + continue; + else + goto err_out; + } + + ret = setup_feedback_loop(dev, np, reg_data, num_reg_data, uv); + if (ret) + goto err_out; + } of_node_put(nproot); return 0; + +err_out: + of_node_put(np); + of_node_put(nproot); + + return ret; } static int bd718xx_probe(struct platform_device *pdev) @@ -1432,8 +1580,10 @@ static int bd718xx_probe(struct platform_device *pdev) * be affected by PMIC state machine - Eg. regulator is likely to stay * on even in SUSPEND */ - get_hw_controlled_regulators(pdev->dev.parent, reg_data, num_reg_data, + err = get_special_regulators(pdev->dev.parent, reg_data, num_reg_data, &omit_enable); + if (err) + return err; for (i = 0; i < num_reg_data; i++) { |