Re: [PATCH v2 3/4] regulator: add SCMI driver
From: Cristian Marussi
Date: Fri Oct 16 2020 - 12:55:12 EST
On Fri, Oct 16, 2020 at 04:09:42PM +0200, Etienne Carriere wrote:
> Hi Cristian,
>
> Some minor comments...
>
> Etienne
>
>
> On Thu, 15 Oct 2020 at 17:40, Cristian Marussi <cristian.marussi@xxxxxxx> wrote:
> >
> > Add a simple regulator based on SCMI Voltage Domain Protocol.
> >
> > Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
> > ----
> > v1 --> v2
> > - removed duplicate regulator naming
> > - removed redundant .get/set_voltage ops: only _sel variants implemented
> > - removed condexpr on fail path to increase readability
> >
> > v0 --> v1
> > - fixed init_data constraint parsing
> > - fixes for v5.8 (linear_range.h)
> > - fixed commit message content and subject line format
> > - factored out SCMI core specific changes to distinct patch
> > - reworked Kconfig and Makefile to keep proper alphabetic order
> > - fixed SPDX comment style
> > - removed unneeded inline functions
> > - reworked conditionals for legibility
> > - fixed some return paths to properly report SCMI original errors codes
> > - added some more descriptive error messages when fw returns invalid ranges
> > - removed unneeded explicit devm_regulator_unregister from .remove()
> > ---
> > drivers/regulator/Kconfig | 9 +
> > drivers/regulator/Makefile | 1 +
> > drivers/regulator/scmi-regulator.c | 453 +++++++++++++++++++++++++++++
> > 3 files changed, 463 insertions(+)
> > create mode 100644 drivers/regulator/scmi-regulator.c
> >
> > diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
> > index de17ef7e18f0..6d3a10cb9833 100644
> > --- a/drivers/regulator/Kconfig
> > +++ b/drivers/regulator/Kconfig
> > @@ -155,6 +155,15 @@ config REGULATOR_ARIZONA_MICSUPP
> > and Wolfson Microelectronic Arizona codecs
> > devices.
> >
> > +config REGULATOR_ARM_SCMI
> > + tristate "SCMI based regulator driver"
> > + depends on ARM_SCMI_PROTOCOL && OF
> > + help
> > + This adds the regulator driver support for ARM platforms using SCMI
> > + protocol for device voltage management.
> > + This driver uses SCMI Message Protocol driver to interact with the
> > + firmware providing the device Voltage functionality.
> > +
> > config REGULATOR_AS3711
> > tristate "AS3711 PMIC"
> > depends on MFD_AS3711
> > diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
> > index d8d3ecf526a8..0532a7393d5d 100644
> > --- a/drivers/regulator/Makefile
> > +++ b/drivers/regulator/Makefile
> > @@ -24,6 +24,7 @@ obj-$(CONFIG_REGULATOR_AD5398) += ad5398.o
> > obj-$(CONFIG_REGULATOR_ANATOP) += anatop-regulator.o
> > obj-$(CONFIG_REGULATOR_ARIZONA_LDO1) += arizona-ldo1.o
> > obj-$(CONFIG_REGULATOR_ARIZONA_MICSUPP) += arizona-micsupp.o
> > +obj-$(CONFIG_REGULATOR_ARM_SCMI) += scmi-regulator.o
> > obj-$(CONFIG_REGULATOR_AS3711) += as3711-regulator.o
> > obj-$(CONFIG_REGULATOR_AS3722) += as3722-regulator.o
> > obj-$(CONFIG_REGULATOR_AXP20X) += axp20x-regulator.o
> > diff --git a/drivers/regulator/scmi-regulator.c b/drivers/regulator/scmi-regulator.c
> > new file mode 100644
> > index 000000000000..e4e7d0345723
> > --- /dev/null
> > +++ b/drivers/regulator/scmi-regulator.c
> > @@ -0,0 +1,453 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +//
> > +// System Control and Management Interface (SCMI) based regulator driver
> > +//
> > +// Copyright (C) 2020 ARM Ltd.
> > +//
> > +// Implements a regulator driver on top of the SCMI Voltage Protocol.
> > +//
> > +// The ARM SCMI Protocol aims in general to hide as much as possible all the
> > +// underlying operational details while providing an abstracted interface for
> > +// its users to operate upon: as a consequence the resulting operational
> > +// capabilities and configurability of this regulator device are much more
> > +// limited than the ones usually available on a standard physical regulator.
> > +//
> > +// The supported SCMI regulator ops are restricted to the bare minimum:
> > +//
> > +// - 'status_ops': enable/disable/is_enabled
> > +// - 'voltage_ops': get_voltage_sel/set_voltage_sel
> > +// list_voltage/map_voltage
> > +//
> > +// Each SCMI regulator instance is associated, through the means of a proper DT
> > +// entry description, to a specific SCMI Voltage Domain.
> > +
> > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> > +
> > +#include <linux/linear_range.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/regulator/driver.h>
> > +#include <linux/regulator/machine.h>
> > +#include <linux/regulator/of_regulator.h>
> > +#include <linux/scmi_protocol.h>
> > +#include <linux/slab.h>
> > +#include <linux/types.h>
> > +
> > +struct scmi_regulator {
> > + u32 id;
> > + struct scmi_device *sdev;
> > + struct regulator_dev *rdev;
> > + struct device_node *of_node;
> > + struct regulator_desc desc;
> > + struct regulator_config conf;
> > +};
> > +
> > +struct scmi_regulator_info {
> > + int num_doms;
> > + struct scmi_regulator **sregv;
> > +};
> > +
> > +static int scmi_reg_enable(struct regulator_dev *rdev)
> > +{
> > + struct scmi_regulator *sreg = rdev_get_drvdata(rdev);
> > + const struct scmi_handle *handle = sreg->sdev->handle;
> > +
> > + return handle->voltage_ops->config_set(handle, sreg->id,
> > + SCMI_VOLTAGE_ARCH_STATE_ON);
> > +}
> > +
> > +static int scmi_reg_disable(struct regulator_dev *rdev)
> > +{
> > + struct scmi_regulator *sreg = rdev_get_drvdata(rdev);
> > + const struct scmi_handle *handle = sreg->sdev->handle;
> > +
> > + return handle->voltage_ops->config_set(handle, sreg->id,
> > + SCMI_VOLTAGE_ARCH_STATE_OFF);
> > +}
> > +
> > +static int scmi_reg_is_enabled(struct regulator_dev *rdev)
> > +{
> > + int ret;
> > + u32 config;
> > + struct scmi_regulator *sreg = rdev_get_drvdata(rdev);
> > + const struct scmi_handle *handle = sreg->sdev->handle;
> > +
> > + ret = handle->voltage_ops->config_get(handle, sreg->id,
> > + &config);
> > + if (ret) {
> > + dev_err(&sreg->sdev->dev,
> > + "Error %d reading regulator %s status.\n",
> > + ret, sreg->desc.name);
> > + return 0;
> > + }
> > +
> > + return config & SCMI_VOLTAGE_ARCH_STATE_ON;
> > +}
> > +
> > +static int scmi_reg_get_voltage_sel(struct regulator_dev *rdev)
> > +{
> > + int ret;
> > + s32 volt_uV;
> > + struct scmi_regulator *sreg = rdev_get_drvdata(rdev);
> > + const struct scmi_handle *handle = sreg->sdev->handle;
> > +
> > + ret = handle->voltage_ops->level_get(handle, sreg->id, &volt_uV);
> > + if (ret)
> > + return ret;
> > +
> > + return sreg->desc.ops->map_voltage(rdev, volt_uV, volt_uV);
> > +}
> > +
> > +static int scmi_reg_set_voltage_sel(struct regulator_dev *rdev,
> > + unsigned int selector)
> > +{
> > + int ret;
> > + s32 volt_uV;
> > + struct scmi_regulator *sreg = rdev_get_drvdata(rdev);
> > + const struct scmi_handle *handle = sreg->sdev->handle;
> > +
> > + volt_uV = sreg->desc.ops->list_voltage(rdev, selector);
> > + if (volt_uV <= 0)
> > + return -EINVAL;
> > +
> > + ret = handle->voltage_ops->level_set(handle, sreg->id, 0x0, volt_uV);
> > + if (ret)
> > + return ret;
> > +
> > + return ret;
>
> return handle->voltage_ops->level_set(handle, sreg->id, 0x0, volt_uV);
>
> > +}
> > +
> > +static const struct regulator_ops scmi_reg_fixed_ops = {
> > + .enable = scmi_reg_enable,
> > + .disable = scmi_reg_disable,
> > + .is_enabled = scmi_reg_is_enabled,
> > +};
> > +
> > +static const struct regulator_ops scmi_reg_linear_ops = {
> > + .enable = scmi_reg_enable,
> > + .disable = scmi_reg_disable,
> > + .is_enabled = scmi_reg_is_enabled,
> > + .get_voltage_sel = scmi_reg_get_voltage_sel,
> > + .set_voltage_sel = scmi_reg_set_voltage_sel,
> > + .list_voltage = regulator_list_voltage_linear,
> > + .map_voltage = regulator_map_voltage_linear,
> > +};
> > +
> > +static const struct regulator_ops scmi_reg_range_ops = {
> > + .enable = scmi_reg_enable,
> > + .disable = scmi_reg_disable,
> > + .is_enabled = scmi_reg_is_enabled,
> > + .get_voltage_sel = scmi_reg_get_voltage_sel,
> > + .set_voltage_sel = scmi_reg_set_voltage_sel,
> > + .list_voltage = regulator_list_voltage_linear_range,
> > + .map_voltage = regulator_map_voltage_linear_range,
> > +};
> > +
> > +static const struct regulator_ops scmi_reg_discrete_ops = {
> > + .enable = scmi_reg_enable,
> > + .disable = scmi_reg_disable,
> > + .is_enabled = scmi_reg_is_enabled,
> > + .get_voltage_sel = scmi_reg_get_voltage_sel,
> > + .set_voltage_sel = scmi_reg_set_voltage_sel,
> > + .list_voltage = regulator_list_voltage_table,
> > + .map_voltage = regulator_map_voltage_iterate,
> > +};
> > +
> > +static int
> > +scmi_config_linear_regulator_mappings(struct scmi_regulator *sreg,
> > + const struct scmi_voltage_info *vinfo)
> > +{
> > + /*
> > + * Note that SCMI voltage domains describable by linear ranges
> > + * (segments) {low, high, step} are guaranteed to come in triplets by
> > + * the SCMI Voltage Domain protocol support itself.
> > + */
> > + if (vinfo->num_levels == 3) {
> > + s32 delta_uV;
> > +
> > + delta_uV = (vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_HIGH] -
> > + vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_LOW]);
> > + /* Rule out buggy negative-intervals answers from fw */
> > + if (delta_uV < 0) {
> > + dev_err(&sreg->sdev->dev,
> > + "Invalid volt-range %d-%duV for domain %d\n",
> > + vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_LOW],
> > + vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_HIGH],
> > + sreg->id);
> > + return -EINVAL;
> > + }
> > +
> > + if (!delta_uV) {
> > + /* Just one fixed voltage exposed by SCMI */
> > + sreg->desc.fixed_uV =
> > + vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_LOW];
> > + sreg->desc.n_voltages = 1;
> > + sreg->desc.ops = &scmi_reg_fixed_ops;
> > + } else {
> > + /* One simple linear mapping. */
> > + sreg->desc.min_uV =
> > + vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_LOW];
> > + sreg->desc.uV_step =
> > + vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_STEP];
> > + sreg->desc.linear_min_sel = 0;
> > + sreg->desc.n_voltages = delta_uV / sreg->desc.uV_step;
> > + sreg->desc.ops = &scmi_reg_linear_ops;
> > + }
> > + } else {
> > + /* Multiple linear mappings. */
>
> I don't see this multi-linear mapping in the v3.0 beta of the spec.
> Is it something planned?
>
No, it was indeed something included in previous spec iterations (multiple triplets)
but now removed, as said in previous patch, I forgot to remove this
redundant support. I'll do in V3.
> > + int i, num_ranges, last_max = -1;
> > + struct linear_range *lr;
> > +
> > + num_ranges = vinfo->num_levels / 3;
> > + lr = devm_kcalloc(&sreg->sdev->dev, num_ranges,
> > + sizeof(*lr), GFP_KERNEL);
> > + if (!lr)
> > + return -ENOMEM;
> > +
> > + sreg->desc.n_linear_ranges = num_ranges;
> > + sreg->desc.linear_ranges = lr;
> > + for (i = 0; num_ranges; num_ranges--, i += 3, lr++) {
> > + s32 delta_uV;
> > +
> > + lr->min =
> > + vinfo->levels_uv[i + SCMI_VOLTAGE_SEGMENT_LOW];
> > + lr->step =
> > + vinfo->levels_uv[i + SCMI_VOLTAGE_SEGMENT_STEP];
> > + delta_uV =
> > + vinfo->levels_uv[i + SCMI_VOLTAGE_SEGMENT_HIGH] -
> > + lr->min;
> > + if (delta_uV <= 0 || !(delta_uV / lr->step)) {
> > + dev_err(&sreg->sdev->dev,
> > + "Invalid volt-range %d-%duV for domain %d\n",
> > + vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_LOW],
> > + vinfo->levels_uv[SCMI_VOLTAGE_SEGMENT_HIGH],
> > + sreg->id);
> > + return -EINVAL;
> > + }
> > + lr->max_sel = delta_uV / lr->step - 1;
> > + lr->min_sel = last_max + 1;
> > + last_max = lr->max_sel;
> > + }
> > + sreg->desc.n_voltages = last_max + 1;
> > + sreg->desc.ops = &scmi_reg_range_ops;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int
> > +scmi_config_discrete_regulator_mappings(struct scmi_regulator *sreg,
> > + const struct scmi_voltage_info *vinfo)
> > +{
> > + /* Discrete non linear levels are mapped to volt_table */
> > + sreg->desc.n_voltages = vinfo->num_levels;
> > + if (sreg->desc.n_voltages > 1) {
> > + sreg->desc.volt_table = (const unsigned int *)vinfo->levels_uv;
> > + sreg->desc.ops = &scmi_reg_discrete_ops;
> > + } else {
> > + sreg->desc.fixed_uV = vinfo->levels_uv[0];
> > + sreg->desc.ops = &scmi_reg_fixed_ops;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int scmi_regulator_common_init(struct scmi_regulator *sreg)
> > +{
> > + int ret;
> > + const struct scmi_handle *handle = sreg->sdev->handle;
> > + struct device *dev = &sreg->sdev->dev;
> > + const struct scmi_voltage_info *vinfo;
> > +
> > + vinfo = handle->voltage_ops->info_get(handle, sreg->id);
> > + if (!vinfo)
> > + return -ENODEV;
> > +
> > + if (!vinfo->num_levels)
> > + return -EINVAL;
> > +
> > + /*
> > + * Regulator framework does not fully support negative voltages
> > + * so we discard any voltage domain reported as supporting negative
> > + * voltages: as a consequence each levels_uv entry is guaranteed to
> > + * be non-negative from here on.
> > + */
> > + if (vinfo->negative_volts_allowed) {
> > + dev_warn(dev, "Negative voltages NOT supported...skip %s\n",
> > + sreg->of_node->full_name);
> > + return -EOPNOTSUPP;
> > + }
> > +
> > + sreg->desc.name = devm_kasprintf(dev, GFP_KERNEL, "%s", vinfo->name);
> > + if (!sreg->desc.name)
> > + return -ENOMEM;
> > +
> > + sreg->desc.id = sreg->id;
> > + sreg->desc.type = REGULATOR_VOLTAGE;
> > + sreg->desc.owner = THIS_MODULE;
> > + sreg->desc.of_match = sreg->of_node->name;
> > + sreg->desc.regulators_node = "regulators";
> > + if (vinfo->segmented)
> > + ret = scmi_config_linear_regulator_mappings(sreg, vinfo);
> > + else
> > + ret = scmi_config_discrete_regulator_mappings(sreg, vinfo);
> > + if (ret)
> > + return ret;
> > +
> > + sreg->conf.dev = dev;
> > + sreg->conf.driver_data = sreg;
> > +
> > + return 0;
> > +}
> > +
> > +static int process_scmi_regulator_of_node(struct scmi_device *sdev,
> > + struct device_node *np,
> > + struct scmi_regulator_info *rinfo)
> > +{
> > + u32 dom, ret;
> > +
> > + ret = of_property_read_u32(np, "reg", &dom);
> > + if (ret)
> > + return ret;
> > +
> > + if (dom >= rinfo->num_doms)
> > + return -ENODEV;
> > +
> > + if (rinfo->sregv[dom]) {
> > + dev_err(&sdev->dev,
> > + "SCMI Voltage Domain %d already in use. Skipping: %s\n",
> > + dom, np->full_name);
> > + return -EINVAL;
> > + }
> > +
> > + rinfo->sregv[dom] = devm_kzalloc(&sdev->dev,
> > + sizeof(struct scmi_regulator),
> > + GFP_KERNEL);
> > + if (!rinfo->sregv[dom])
> > + return -ENOMEM;
> > +
> > + rinfo->sregv[dom]->id = dom;
> > + rinfo->sregv[dom]->sdev = sdev;
> > + /* get hold of good nodes */
> > + of_node_get(np);
> > + rinfo->sregv[dom]->of_node = np;
> > + dev_info(&sdev->dev,
> > + "Found valid SCMI Regulator -- OF node [%d] -> %s\n",
> > + dom, np->full_name);
> > +
> > + return ret;
>
> suggest return 0; here.
Ok.
>
> > +}
> > +
> > +static int scmi_regulator_probe(struct scmi_device *sdev)
> > +{
> > + int d, ret, num_doms;
> > + struct device_node *np, *child;
> > + const struct scmi_handle *handle = sdev->handle;
> > + struct scmi_regulator_info *rinfo;
> > +
> > + if (!handle || !handle->voltage_ops)
> > + return -ENODEV;
> > +
> > + num_doms = handle->voltage_ops->num_domains_get(handle);
> > + if (num_doms <= 0) {
> > + if (!num_doms) {
> > + dev_err(&sdev->dev,
> > + "number of voltage domains invalid\n");
> > + num_doms = -EINVAL;
> > + } else {
> > + dev_err(&sdev->dev,
> > + "failed to get voltage domains - err:%d\n",
> > + num_doms);
> > + }
> > +
> > + return num_doms;
> > + }
> > +
> > + rinfo = devm_kzalloc(&sdev->dev, sizeof(*rinfo), GFP_KERNEL);
> > + if (!rinfo)
> > + return -ENOMEM;
> > +
> > + /* Allocate pointers' array for all possible domains */
> > + rinfo->sregv = devm_kcalloc(&sdev->dev, num_doms,
> > + sizeof(rinfo->sregv), GFP_KERNEL);
> > + if (!rinfo->sregv)
> > + return -ENOMEM;
> > +
> > + rinfo->num_doms = num_doms;
> > + /*
> > + * Start collecting into rinfo->sregv possibly good SCMI Regulators as
> > + * described by a well-formed DT entry and associated with an existing
> > + * plausible SCMI Voltage Domain number, all belonging to this SCMI
> > + * platform instance node (handle->dev->of_node).
> > + */
> > + np = of_find_node_by_name(handle->dev->of_node, "regulators");
> > + for_each_child_of_node(np, child) {
> > + ret = process_scmi_regulator_of_node(sdev, child, rinfo);
> > + /* abort on any mem issue */
> > + if (ret == -ENOMEM)
> > + return ret;
> > + }
> > +
> > + /*
> > + * Register a regulator for each valid regulator-DT-entry that we
> > + * can successfully reach via SCMI
> > + */
> > + for (d = 0; d < num_doms; d++) {
> > + struct scmi_regulator *sreg = rinfo->sregv[d];
> > +
> > + if (!sreg)
> > + continue;
> > + ret = scmi_regulator_common_init(sreg);
> > + if (ret)
> > + continue;
> > + sreg->rdev = devm_regulator_register(&sdev->dev, &sreg->desc,
> > + &sreg->conf);
> > + if (IS_ERR(sreg->rdev)) {
> > + sreg->rdev = NULL;
> > + continue;
> > + }
> > +
> > + dev_info(&sdev->dev,
> > + "Regulator %s registered for domain [%d](%s)\n",
> > + sreg->desc.name, sreg->id, sreg->desc.name);
>
> Maybe not display sreg->desc.name twice.
>
Yes does not make any sense indeed now that I have only one name o_O
> > + }
> > +
> > + dev_set_drvdata(&sdev->dev, rinfo);
> > +
> > + return 0;
> > +}
> > +
> > +static void scmi_regulator_remove(struct scmi_device *sdev)
> > +{
> > + int d;
> > + struct scmi_regulator_info *rinfo;
> > +
> > + rinfo = dev_get_drvdata(&sdev->dev);
> > + if (!rinfo)
> > + return;
> > +
> > + for (d = 0; d < rinfo->num_doms; d++) {
> > + if (!rinfo->sregv[d])
> > + continue;
> > + of_node_put(rinfo->sregv[d]->of_node);
> > + }
> > +}
> > +
> > +static const struct scmi_device_id scmi_regulator_id_table[] = {
> > + { SCMI_PROTOCOL_VOLTAGE, "regulator" },
> > + { },
> > +};
> > +MODULE_DEVICE_TABLE(scmi, scmi_regulator_id_table);
> > +
> > +static struct scmi_driver scmi_drv = {
> > + .name = "scmi-regulator",
> > + .probe = scmi_regulator_probe,
> > + .remove = scmi_regulator_remove,
> > + .id_table = scmi_regulator_id_table,
> > +};
> > +
> > +module_scmi_driver(scmi_drv);
> > +
> > +MODULE_AUTHOR("Cristian Marussi <cristian.marussi@xxxxxxx>");
> > +MODULE_DESCRIPTION("ARM SCMI regulator driver");
> > +MODULE_LICENSE("GPL v2");
> > --
> > 2.17.1
> >
Thanks
Cristian