Re: [PATCH 01/13] clk: tegra: Add binding for the Tegra124 DFLL clocksource
From: Tuomas Tynkkynen <hidden>
Date: 2014-07-15 20:23:47
Also in:
linux-arm-kernel, linux-pm, linux-tegra, lkml
Subsystem:
the rest, voltage and current regulator framework · Maintainers:
Linus Torvalds, Liam Girdwood, Mark Brown
On 14/07/14 13:22, Mark Brown wrote:
* PGP Signed by an unknown key On Mon, Jul 14, 2014 at 11:24:35AM +0200, Thierry Reding wrote:quoted
On Mon, Jul 14, 2014 at 10:12:33AM +0100, Mark Brown wrote:quoted
quoted
The selector value is opaque, it's entirely up to the driver to define it. If you could tell me what "this" is I might be able to advise on how to do it.quoted
Tegra124 (and later, also some earlier variants) have this DFLL clock that can program a PMIC automatically depending on the CPU frequency. This DT binding did propose putting this into device tree as a table of <frequency value> pairs where the frequency corresponds to the CPU frequency and the value is the register value to be programmed into the PMIC by the DFLL hardware (there are two additional properties to define the slave address and the register offset).quoted
Andrew proposed that this table could instead be built by using regulator_list_voltage() instead. However, due to the fact that the DFLL hardware needs to know the immediate value to write into a register, the requirement would be for a 1:1 mapping between selector and register value. Given that the API needs to cover the general case I don't see how it could practically ensure this.Well, if you're going to do that you've already created a private API between the regulator driver and the device since you're assuming that the device is controlled only by register writes to a single register bitfield which isn't always the case. As with all these things it would also be better to extend the regulator API so that users like this can discover the register address and so on too rather than having to replicate that information in the device tree. No sense in having to specify this information multiple times.
That sounds indeed useful for this case. How'd the following interface sound for the register offset / selector-to-register-value conversion? The I2C address would be a bit trickier to get as it would touch the regmap stuff as well, but perhaps it would be a good idea to have a phandle to the I2C device itself, and then parse the reg field for the address.
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index c563d93..a5efb96 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c@@ -2228,6 +2228,63 @@ int regulator_list_voltage(struct regulator *regulator, unsigned selector) EXPORT_SYMBOL_GPL(regulator_list_voltage); /** + * regulator_get_hardware_vsel_register - get the HW voltage selector register + * @regulator: regulator source + * @vsel_reg: voltage selector register, output parameter + * @vsel_mask: mask for voltage selector bitfield, output parameter + * + * Returns the hardware register offset and bitmask used for setting the + * regulator voltage. This might be useful when configuring voltage-scaling + * hardware or firmware that can make I2C requests behind the kernel's back, + * for example. + * + * On success, the output parameters @vsel_reg and @vsel_mask are filled in + * and 0 is returned, otherwise a negative errno is returned. + */ +int regulator_get_hardware_vsel_register(struct regulator *regulator, + unsigned *vsel_reg, + unsigned *vsel_mask) +{ + struct regulator_dev *rdev = regulator->rdev; + struct regulator_ops *ops = rdev->desc->ops; + + if (ops->set_voltage_sel != regulator_set_voltage_sel_regmap) + return -EOPNOTSUPP; + + *vsel_reg = rdev->desc->vsel_reg; + *vsel_mask = rdev->desc->vsel_mask; + + return 0; +} +EXPORT_SYMBOL_GPL(regulator_get_hardware_vsel_register); + +/** + * regulator_list_hardware_vsel - get the HW-specific register value for a selector + * @regulator: regulator source + * @selector: identify voltage to list + * + * Converts the selector to a hardware-specific voltage selector that can be + * directly written to the regulator registers. The address of the voltage + * register can be determined by calling @regulator_get_hardware_vsel_register. + * + * On error a negative errno is returned. + */ +int regulator_list_hardware_vsel(struct regulator *regulator, + unsigned selector) +{ + struct regulator_dev *rdev = regulator->rdev; + struct regulator_ops *ops = rdev->desc->ops; + + if (selector >= rdev->desc->n_voltages) + return -EINVAL; + if (ops->set_voltage_sel != regulator_set_voltage_sel_regmap) + return -EOPNOTSUPP; + + return selector; +} +EXPORT_SYMBOL_GPL(regulator_list_hardware_vsel); + +/** * regulator_get_linear_step - return the voltage step size between VSEL values * @regulator: regulator source *
diff --git a/include/linux/regulator/consumer.h b/include/linux/regulator/consumer.h
index 14ec18d..fe4cdb2 100644
--- a/include/linux/regulator/consumer.h
+++ b/include/linux/regulator/consumer.h@@ -215,6 +215,12 @@ int regulator_set_optimum_mode(struct regulator *regulator, int load_uA); int regulator_allow_bypass(struct regulator *regulator, bool allow); +int regulator_get_hardware_vsel_register(struct regulator *regulator, + unsigned *vsel_reg, + unsigned *vsel_mask); +int regulator_list_hardware_vsel(struct regulator *regulator, + unsigned selector); + /* regulator notifier block */ int regulator_register_notifier(struct regulator *regulator, struct notifier_block *nb);
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nvpublic