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SubjectRe: [PATCH V2 3/4] soc: imx: Add generic blk-ctl driver
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On 2021/5/4 17:47, Lucas Stach wrote:
> Am Freitag, dem 30.04.2021 um 13:27 +0800 schrieb Peng Fan (OSS):
>> From: Peng Fan <peng.fan@nxp.com>
>>
>> The i.MX8MM introduces an IP named BLK_CTL and usually is comprised of
>> some GPRs.
>>
>> The GPRs has some clock bits and reset bits, but here we take it
>> as virtual PDs, because of the clock and power domain A/B lock issue
>> when taking it as a clock controller.
>>
>> For some bits, it might be good to also make it as a reset controller,
>> but to i.MX8MM, we not add that support for now.
>>
>> Signed-off-by: Peng Fan <peng.fan@nxp.com>
>> ---
>>  drivers/soc/imx/Makefile | 2 +-
>>  drivers/soc/imx/blk-ctl.c | 303 ++++++++++++++++++++++++++++++++++++++
>>  drivers/soc/imx/blk-ctl.h | 76 ++++++++++
>>  3 files changed, 380 insertions(+), 1 deletion(-)
>>  create mode 100644 drivers/soc/imx/blk-ctl.c
>>  create mode 100644 drivers/soc/imx/blk-ctl.h
>>
>> diff --git a/drivers/soc/imx/Makefile b/drivers/soc/imx/Makefile
>> index 078dc918f4f3..d3d2b49a386c 100644
>> --- a/drivers/soc/imx/Makefile
>> +++ b/drivers/soc/imx/Makefile
>> @@ -4,4 +4,4 @@ obj-$(CONFIG_ARCH_MXC) += soc-imx.o
>>  endif
>>  obj-$(CONFIG_HAVE_IMX_GPC) += gpc.o
>>  obj-$(CONFIG_IMX_GPCV2_PM_DOMAINS) += gpcv2.o
>> -obj-$(CONFIG_SOC_IMX8M) += soc-imx8m.o
>> +obj-$(CONFIG_SOC_IMX8M) += soc-imx8m.o blk-ctl.o
>> diff --git a/drivers/soc/imx/blk-ctl.c b/drivers/soc/imx/blk-ctl.c
>> new file mode 100644
>> index 000000000000..1f764dfd308d
>> --- /dev/null
>> +++ b/drivers/soc/imx/blk-ctl.c
>> @@ -0,0 +1,303 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright 2021 NXP.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm_runtime.h>
>> +#include <linux/regmap.h>
>> +#include <linux/slab.h>
>> +#include <linux/string.h>
>> +#include <linux/types.h>
>> +#include <linux/pm_domain.h>
>> +#include <linux/reset-controller.h>
>> +
>> +#include "blk-ctl.h"
>> +
>> +static inline struct imx_blk_ctl_domain *to_imx_blk_ctl_pd(struct generic_pm_domain *genpd)
>> +{
>> + return container_of(genpd, struct imx_blk_ctl_domain, pd);
>> +}
>> +
>> +static int imx_blk_ctl_enable_hsk(struct device *dev)
>> +{
>> + struct imx_blk_ctl *blk_ctl = dev_get_drvdata(dev);
>> + const struct imx_blk_ctl_hw *hw = &blk_ctl->dev_data->hw_hsk;
>> + struct regmap *regmap = blk_ctl->regmap;
>> + int ret;
>> +
>> +
>> + if (hw->flags & IMX_BLK_CTL_PD_RESET)
>> + ret = regmap_update_bits(regmap, hw->rst_offset, hw->rst_mask, hw->rst_mask);
>> +
>> + ret = regmap_update_bits(regmap, hw->offset, hw->mask, hw->mask);
>> +
>> + /* Wait for handshake */
>> + udelay(5);
>> +
>> + return ret;
>> +}
>> +
>> +int imx_blk_ctl_power_off(struct generic_pm_domain *domain)
>> +{
>> + struct imx_blk_ctl_domain *pd;
>> + struct imx_blk_ctl *blk_ctl;
>> + const struct imx_blk_ctl_hw *hw;
>> + struct regmap *regmap;
>> + int ret;
>> +
>> + pd = to_imx_blk_ctl_pd(domain);
>> + blk_ctl = pd->blk_ctl;
>> + regmap = blk_ctl->regmap;
>> + hw = &blk_ctl->dev_data->pds[pd->id];
>> +
>> + ret = clk_bulk_prepare_enable(blk_ctl->num_clks, blk_ctl->clks);
>> + if (ret)
>> + return ret;
>
> This looks a bit strange to me. Does that mean that you keep all the
> CCM clocks going into the blkctl enabled as long as one of the blkctl
> virtual power domains is up?

No. The clocks are disable unprepared when this function finish.
The clocks are only used for setting blk ctl bits and handshake.

I would have expected each virtual PD to
> have a list of clock names that need to be enabled, to make this more
> selective.
>
> I haven't completely thought it through if this is a problem, but I
> could see some CCM PLLs running without a reason if all CCM clocks are
> kept enabled. This surely is something we want to avoid from a pwoer
> consumption PoV.

I thought to add selective clocks for each virtual PD, but that makes
the design completed, and the clocks(gate) are only enabled for a little
while, so I think compared with the software complexity, the little
benifit of power could be ignored?

>
>> +
>> + ret = regmap_update_bits(regmap, hw->offset, hw->mask, 0);
>> + if (ret)
>> + goto hsk_fail;
>> +
>> + if (hw->flags & IMX_BLK_CTL_PD_RESET)
>> + ret = regmap_update_bits(regmap, hw->rst_offset, hw->rst_mask, 0);
>> +
>> + if (atomic_dec_and_test(&blk_ctl->power_count)) {
>> + ret = imx_blk_ctl_enable_hsk(blk_ctl->dev);
>> + if (ret) {
>> + dev_err(blk_ctl->dev, "Hankshake fail\n");
>> + goto hsk_fail;
>> + }
>> + }
>> +
>> +hsk_fail:
>> + clk_bulk_disable_unprepare(blk_ctl->num_clks, blk_ctl->clks);
>> +
>> + return ret;
>> +}
>> +
>> +int imx_blk_ctl_power_on(struct generic_pm_domain *domain)
>> +{
>> + struct imx_blk_ctl_domain *pd;
>> + struct regmap *regmap;
>> + const struct imx_blk_ctl_hw *hw;
>> + int ret;
>> + struct imx_blk_ctl *blk_ctl;
>> +
>> + pd = to_imx_blk_ctl_pd(domain);
>> + blk_ctl = pd->blk_ctl;
>> + regmap = blk_ctl->regmap;
>> + hw = &blk_ctl->dev_data->pds[pd->id];
>> +
>> + ret = clk_bulk_prepare_enable(blk_ctl->num_clks, blk_ctl->clks);
>> + if (ret)
>> + return ret;
>> +
>> + if ((atomic_read(&blk_ctl->power_count) == 0)) {
>> + ret = imx_blk_ctl_enable_hsk(blk_ctl->dev);
>> + if (ret) {
>> + dev_err(blk_ctl->dev, "Hankshake fail\n");
>> + goto disable_clk;
>> + }
>> + }
>
> This is bogus. The variable isn't used as a atomic, if at all this
> should use atomic_inc_return, but I think even that isn't correct in
> that case. imx_blk_ctl_enable_hsk() includes a wait time, so if two
> paths call this function at the same time, the second caller would be
> able to overtake the first one, which is still waiting for the
> handshake to complete, effectively skipping the handshake. This needs a
> proper lock, as this function isn't called from a performance critical
> path it makes no sense to try to optimize this with an atomic counter,
> rather than going with a mutex.

I see. Will use a mutex here.

>
>> +
>> + if (hw->flags & IMX_BLK_CTL_PD_RESET)
>> + ret = regmap_update_bits(regmap, hw->rst_offset, hw->rst_mask, 0);
>> +
>> + /* Wait for reset propagate */
>> + udelay(5);
>> +
>> + if (hw->flags & IMX_BLK_CTL_PD_RESET)
>> + ret = regmap_update_bits(regmap, hw->rst_offset, hw->rst_mask, hw->rst_mask);
>> +
>> + ret = regmap_update_bits(regmap, hw->offset, hw->mask, hw->mask);
>> + if (ret)
>> + goto disable_clk;
>> +
>> + atomic_inc(&blk_ctl->power_count);
>> +
>> +disable_clk:
>> + clk_bulk_disable_unprepare(blk_ctl->num_clks, blk_ctl->clks);
>> +
>> + return ret;
>> +}
>> +
>> +static int imx_blk_ctl_attach_pd(struct device *dev, struct device **devs, char **pd_names,
>> + u32 num_pds)
>> +{
>> + int i, ret;
>> +
>> + if (!pd_names)
>> + return 0;
>> +
>> + if (dev->pm_domain) {
>> + devs[0] = dev;
>> + pm_runtime_enable(dev);
>> + return 0;
>> + }
>> +
>> + for (i = 0; i < num_pds; i++) {
>> + devs[i] = dev_pm_domain_attach_by_name(dev, pd_names[i]);
>> + if (IS_ERR_OR_NULL(devs[i])) {
>> + ret = PTR_ERR(devs[i]) ? : -ENODATA;
>> + goto detach_pm;
>> + }
>> + }
>> +
>> + return 0;
>> +
>> +detach_pm:
>> + for (i--; i >= 0; i--)
>> + dev_pm_domain_detach(devs[i], false);
>> +
>> + return ret;
>> +}
>> +
>> +static int imx_blk_ctl_register_pd(struct device *dev)
>> +{
>> + struct imx_blk_ctl *blk_ctl = dev_get_drvdata(dev);
>> + const struct imx_blk_ctl_dev_data *dev_data = blk_ctl->dev_data;
>> + int num = dev_data->pds_num;
>> + struct imx_blk_ctl_domain *domain;
>> + int i, ret;
>> +
>> + blk_ctl->onecell_data.num_domains = num;
>> + blk_ctl->onecell_data.domains = devm_kcalloc(dev, num,
>> + sizeof(struct generic_pm_domain *),
>> + GFP_KERNEL);
>> +
>> + if (!blk_ctl->onecell_data.domains)
>> + return -ENOMEM;
>> +
>> + for (i = 0; i < num; i++) {
>> + domain = devm_kzalloc(dev, sizeof(*domain), GFP_KERNEL);
>> + if (!domain) {
>> + ret = -ENOMEM;
>> + goto remove_genpd;
>> + }
>> + domain->pd.name = dev_data->pds[i].name;
>> + domain->pd.power_off = imx_blk_ctl_power_off;
>> + domain->pd.power_on = imx_blk_ctl_power_on;
>> + domain->blk_ctl = blk_ctl;
>> + domain->id = i;
>> +
>> + ret = pm_genpd_init(&domain->pd, NULL, true);
>> + if (ret)
>> + return ret;
>> +
>> + blk_ctl->onecell_data.domains[i] = &domain->pd;
>> + }
>> +
>> + return 0;
>> +
>> +remove_genpd:
>> + for (i = i - 1; i >= 0; i--)
>> + pm_genpd_remove(blk_ctl->onecell_data.domains[i]);
>> +
>> + return ret;
>> +}
>> +
>> +static int imx_blk_ctl_hook_pd(struct device *dev)
>> +{
>> + struct imx_blk_ctl *blk_ctl = dev_get_drvdata(dev);
>> + const struct imx_blk_ctl_dev_data *dev_data = blk_ctl->dev_data;
>> + const struct imx_blk_ctl_hw *pds = dev_data->pds;
>> + int num_active_pd = dev_data->num_active_pd;
>> + int num = dev_data->pds_num;
>> + struct generic_pm_domain *genpd, *child_genpd;
>> + int ret;
>> + int i, j;
>> +
>> + blk_ctl->active_pds = devm_kcalloc(dev, num_active_pd, sizeof(struct device *), GFP_KERNEL);
>> + if (!blk_ctl->active_pds)
>> + return -ENOMEM;
>> +
>> + ret = imx_blk_ctl_attach_pd(dev, blk_ctl->active_pds, dev_data->active_pd_names,
>> + num_active_pd);
>> + if (ret) {
>> + if (ret == -EPROBE_DEFER)
>> + return ret;
>> + dev_err(dev, "Failed to attach active pd: %d\n", ret);
>> + return ret;
>> + }
>> +
>> + for (i = 0; i < num; i++) {
>> + for (j = 0; j < num_active_pd; j++) {
>> + genpd = pd_to_genpd(blk_ctl->active_pds[j]->pm_domain);
>> + if (!strcmp(genpd->name, pds[i].parent_name))
>> + break;
>> + }
>> +
>> + child_genpd = blk_ctl->onecell_data.domains[i];
>> + if (pm_genpd_add_subdomain(genpd, child_genpd))
>> + pr_warn("failed to add subdomain:\n");
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +int imx_blk_ctl_register(struct device *dev)
>> +{
>> + struct imx_blk_ctl *blk_ctl = dev_get_drvdata(dev);
>> + const struct imx_blk_ctl_dev_data *dev_data = blk_ctl->dev_data;
>> + int num = dev_data->pds_num;
>> + int i, ret;
>> +
>> + if (!blk_ctl)
>> + return -ENODEV;
>> +
>> + ret = imx_blk_ctl_register_pd(dev);
>> + if (ret)
>> + return ret;
>> +
>> + ret = imx_blk_ctl_hook_pd(dev);
>> + if (ret)
>> + goto unregister_pd;
>> +
>> + ret = of_genpd_add_provider_onecell(dev->of_node, &blk_ctl->onecell_data);
>> + if (ret)
>> + goto detach_pd;
>> +
>> + pm_runtime_get_noresume(dev);
>> + pm_runtime_set_active(dev);
>> + pm_runtime_enable(dev);
>> +
>> + pm_runtime_put(dev);
>> +
>> + return 0;
>> +
>> +detach_pd:
>> + for (i = blk_ctl->dev_data->num_active_pd; i >= 0; i--)
>> + dev_pm_domain_detach(blk_ctl->active_pds[i], false);
>> +unregister_pd:
>> + for (i = num - 1; i >= 0; i--)
>> + pm_genpd_remove(blk_ctl->onecell_data.domains[i]);
>> +
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(imx_blk_ctl_register);
>> +
>> +static int __maybe_unused imx_blk_ctl_runtime_suspend(struct device *dev)
>> +{
>> + return 0;
>> +}
>> +
>> +static int __maybe_unused imx_blk_ctl_runtime_resume(struct device *dev)
>> +{
>> + return 0;
>> +}
>
> Why those empty stubs? If you don't need to do anything for
> suspend/resume, just don't add the functions.

ok, will drop in V3.

Thanks,
Peng.

>
>> +
>> +const struct dev_pm_ops imx_blk_ctl_pm_ops = {
>> + SET_RUNTIME_PM_OPS(imx_blk_ctl_runtime_suspend,
>> + imx_blk_ctl_runtime_resume, NULL)
>> + SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
>> + pm_runtime_force_resume)
>> +};
>> +EXPORT_SYMBOL_GPL(imx_blk_ctl_pm_ops);
>> diff --git a/drivers/soc/imx/blk-ctl.h b/drivers/soc/imx/blk-ctl.h
>> new file mode 100644
>> index 000000000000..e736369406a1
>> --- /dev/null
>> +++ b/drivers/soc/imx/blk-ctl.h
>> @@ -0,0 +1,76 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +#ifndef __SOC_IMX_BLK_CTL_H
>> +#define __SOC_IMX_BLK_CTL_H
>> +
>> +enum imx_blk_ctl_pd_type {
>> + BLK_CTL_PD,
>> +};
>> +
>> +struct imx_blk_ctl_hw {
>> + int type;
>> + char *name;
>> + char *parent_name;
>> + u32 offset;
>> + u32 mask;
>> + u32 flags;
>> + u32 id;
>> + u32 rst_offset;
>> + u32 rst_mask;
>> +};
>> +
>> +struct imx_blk_ctl_domain {
>> + struct generic_pm_domain pd;
>> + struct imx_blk_ctl *blk_ctl;
>> + u32 id;
>> +};
>> +
>> +struct imx_blk_ctl_dev_data {
>> + struct regmap_config config;
>> + struct imx_blk_ctl_hw *pds;
>> + struct imx_blk_ctl_hw hw_hsk;
>> + u32 pds_num;
>> + char **active_pd_names;
>> + u32 num_active_pd;
>> +};
>> +
>> +struct imx_blk_ctl {
>> + struct device *dev;
>> + struct regmap *regmap;
>> + struct device **active_pds;
>> + u32 pds_num;
>> + u32 active_pd_count;
>> + struct genpd_onecell_data onecell_data;
>> + const struct imx_blk_ctl_dev_data *dev_data;
>> + struct clk_bulk_data *clks;
>> + u32 num_clks;
>> +
>> + atomic_t power_count;
>> +};
>> +
>> +#define IMX_BLK_CTL(_type, _name, _parent_name, _id, _offset, _mask, _rst_offset, _rst_mask, \
>> + _flags) \
>> + { \
>> + .type = _type, \
>> + .name = _name, \
>> + .parent_name = _parent_name, \
>> + .id = _id, \
>> + .offset = _offset, \
>> + .mask = _mask, \
>> + .flags = _flags, \
>> + .rst_offset = _rst_offset, \
>> + .rst_mask = _rst_mask, \
>> + }
>> +
>> +#define IMX_BLK_CTL_PD(_name, _parent_name, _id, _offset, _mask, _rst_offset, _rst_mask, _flags) \
>> + IMX_BLK_CTL(BLK_CTL_PD, _name, _parent_name, _id, _offset, _mask, _rst_offset, \
>> + _rst_mask, _flags)
>> +
>> +int imx_blk_ctl_register(struct device *dev);
>> +
>> +#define IMX_BLK_CTL_PD_HANDSHAKE BIT(0)
>> +#define IMX_BLK_CTL_PD_RESET BIT(1)
>> +#define IMX_BLK_CTL_PD_BUS BIT(2)
>> +
>> +const extern struct dev_pm_ops imx_blk_ctl_pm_ops;
>> +
>> +#endif
>
>

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