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;
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)
* 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++) {
projects / platform / kernel / linux-rpi.git / commitdiff