Re: [RESEND PATCH v2 2/3] soc: starfive: Add StarFive JH71XX pmu driver

From: Conor Dooley
Date: Mon Dec 19 2022 - 15:40:52 EST

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Hey Walker,

Hopefully just some minor bits here. Hopefully either Emil who has a
board, or someone that knows power management stuff better can give this
a proper review.

On Thu, Dec 08, 2022 at 04:45:22PM +0800, Walker Chen wrote:
> Add pmu driver for the StarFive JH71XX SoC.
>
> As the power domains provider, the Power Management Unit (PMU) is
> designed for including multiple PM domains that can be used for power
> gating of selected IP blocks for power saving by reduced leakage
> current. It accepts software encourage command to switch the power mode
> of SoC.
>
> Signed-off-by: Walker Chen <walker.chen@xxxxxxxxxxxxxxxx>
> ---
> MAINTAINERS | 14 ++
> drivers/soc/Kconfig | 1 +
> drivers/soc/Makefile | 1 +
> drivers/soc/starfive/Kconfig | 11 +
> drivers/soc/starfive/Makefile | 3 +
> drivers/soc/starfive/jh71xx_pmu.c | 396 ++++++++++++++++++++++++++++++
> 6 files changed, 426 insertions(+)
> create mode 100644 drivers/soc/starfive/Kconfig
> create mode 100644 drivers/soc/starfive/Makefile
> create mode 100644 drivers/soc/starfive/jh71xx_pmu.c
>

> +config JH71XX_PMU
> + bool "Support PMU for StarFive JH71XX Soc"
> + depends on PM && (SOC_STARFIVE || COMPILE_TEST)

Why not just do:
depends on PM
depends on SOC_STARFIVE || COMPILE_TEST
I think that way reads a little better.

> + default SOC_STARFIVE
> + select PM_GENERIC_DOMAINS
> + help
> + Say 'y' here to enable support power domain support.
> + In order to meet low power requirements, a Power Management Unit (PMU)
> + is designed for controlling power resources in StarFive JH71XX SoCs.
> diff --git a/drivers/soc/starfive/Makefile b/drivers/soc/starfive/Makefile
> new file mode 100644
> index 000000000000..13b589d6b5f3
> --- /dev/null
> +++ b/drivers/soc/starfive/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +obj-$(CONFIG_JH71XX_PMU) += jh71xx_pmu.o
> diff --git a/drivers/soc/starfive/jh71xx_pmu.c b/drivers/soc/starfive/jh71xx_pmu.c
> new file mode 100644
> index 000000000000..7a0145779e07
> --- /dev/null
> +++ b/drivers/soc/starfive/jh71xx_pmu.c
> @@ -0,0 +1,396 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * StarFive JH71XX PMU (Power Management Unit) Controller Driver
> + *
> + * Copyright (C) 2022 StarFive Technology Co., Ltd.
> + */
> +
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_domain.h>
> +#include <dt-bindings/power/starfive,jh7110-pmu.h>
> +
> +/* register offset */
> +#define JH71XX_PMU_HW_EVENT_ON 0x04
> +#define JH71XX_PMU_HW_EVENT_OFF 0x08
> +#define JH71XX_PMU_SW_TURN_ON_POWER 0x0C
> +#define JH71XX_PMU_SW_TURN_OFF_POWER 0x10
> +#define JH71XX_PMU_SW_ENCOURAGE 0x44
> +#define JH71XX_PMU_INT_MASK 0x48
> +#define JH71XX_PMU_PCH_BYPASS 0x4C
> +#define JH71XX_PMU_PCH_PSTATE 0x50
> +#define JH71XX_PMU_PCH_TIMEOUT 0x54
> +#define JH71XX_PMU_LP_TIMEOUT 0x58
> +#define JH71XX_PMU_HW_TURN_ON 0x5C
> +#define JH71XX_PMU_CURR_POWER_MODE 0x80
> +#define JH71XX_PMU_EVENT_STATUS 0x88
> +#define JH71XX_PMU_INT_STATUS 0x8C
> +
> +/* sw encourage cfg */
> +#define JH71XX_PMU_SW_ENCOURAGE_EN_LO 0x05
> +#define JH71XX_PMU_SW_ENCOURAGE_EN_HI 0x50
> +#define JH71XX_PMU_SW_ENCOURAGE_DIS_LO 0x0A
> +#define JH71XX_PMU_SW_ENCOURAGE_DIS_HI 0xA0
> +#define JH71XX_PMU_SW_ENCOURAGE_ON 0xFF
> +
> +/* pmu int status */
> +#define JH71XX_PMU_INT_SEQ_DONE BIT(0)
> +#define JH71XX_PMU_INT_HW_REQ BIT(1)
> +#define JH71XX_PMU_INT_SW_FAIL GENMASK(3, 2)
> +#define JH71XX_PMU_INT_HW_FAIL GENMASK(5, 4)
> +#define JH71XX_PMU_INT_PCH_FAIL GENMASK(8, 6)
> +#define JH71XX_PMU_INT_FAIL_MASK (JH71XX_PMU_INT_SW_FAIL | \
> + JH71XX_PMU_INT_HW_FAIL | \
> + JH71XX_PMU_INT_PCH_FAIL)
> +#define JH71XX_PMU_INT_ALL_MASK (JH71XX_PMU_INT_SEQ_DONE | \
> + JH71XX_PMU_INT_HW_REQ | \
> + JH71XX_PMU_INT_FAIL_MASK)
> +
> +/*
> + * The time required for switching power status is based on the time
> + * to turn on the largest domain's power, which is at microsecond level
> + */
> +#define JH71XX_PMU_TIMEOUT_US 100
> +
> +struct jh71xx_domain_info {

const char * const name;
unsigned int flags;
u8 bit;

> +};
> +
> +struct jh71xx_pmu_match_data {

const struct jh71xx_domain_info *domain_info;
int num_domains;

Can you switch these two around like so?
> +};
> +
> +struct jh71xx_pmu {
> + struct device *dev;
> + const struct jh71xx_pmu_match_data *match_data;
> + void __iomem *base;
> + spinlock_t lock; /* protects pmu reg */
> + int irq;
> + struct genpd_onecell_data genpd_data;
> + struct generic_pm_domain **genpd;
> +};
> +
> +struct jh71xx_pmu_dev {
> + struct generic_pm_domain genpd;
> + const struct jh71xx_domain_info *domain_info;
> + struct jh71xx_pmu *pmu;

And these two too please in the same way.

> +};
> +
> +static int jh71xx_pmu_get_state(struct jh71xx_pmu_dev *pmd, u32 mask, bool *is_on)
> +{
> + struct jh71xx_pmu *pmu = pmd->pmu;
> +
> + if (!mask) {
> + *is_on = false;
> + return -EINVAL;
> + }
> +
> + *is_on = readl(pmu->base + JH71XX_PMU_CURR_POWER_MODE) & mask;
> +
> + return 0;
> +}
> +
> +static int jh71xx_pmu_set_state(struct jh71xx_pmu_dev *pmd, u32 mask, bool on)
> +{
> + struct jh71xx_pmu *pmu = pmd->pmu;
> + unsigned long flags;
> + u32 val;
> + u32 mode;
> + u32 encourage_lo;
> + u32 encourage_hi;
> + bool is_on;
> + int ret;
> +
> + ret = jh71xx_pmu_get_state(pmd, mask, &is_on);
> + if (ret) {
> + dev_dbg(pmu->dev, "unable to get current state for %s\n",
> + pmd->genpd.name);
> + return ret;
> + }
> +
> + if (is_on == on) {
> + dev_dbg(pmu->dev, "pm domain [%s] is already %sable status.\n",
> + pmd->genpd.name, on ? "en" : "dis");
> + return 0;
> + }
> +
> + spin_lock_irqsave(&pmu->lock, flags);
> +
> + /*
> + * The PMU accepts software encourage to switch power mode in the following 2 steps:
> + *
> + * 1. Configure the register SW_TURN_ON_POWER (offset 0x0c), write 1 to
> + * the bit which power domain will be turn-on, write 0 to the others.

Some grammatical nit picking..

"Configure the register blah (offset 0x0c) by writing 1 to the bit
corresponding to the power domain that will be turned on and writing
zero to the others."

Is that a correct correct summation of the operation?

> + * Likewise, configure the register SW_TURN_OFF_POWER (offset 0x10),
> + * write 1 to the bit which power domain will be turn-off, write 0 to the others.

> + */
> + if (on) {
> + mode = JH71XX_PMU_SW_TURN_ON_POWER;
> + encourage_lo = JH71XX_PMU_SW_ENCOURAGE_EN_LO;
> + encourage_hi = JH71XX_PMU_SW_ENCOURAGE_EN_HI;
> + } else {
> + mode = JH71XX_PMU_SW_TURN_OFF_POWER;
> + encourage_lo = JH71XX_PMU_SW_ENCOURAGE_DIS_LO;
> + encourage_hi = JH71XX_PMU_SW_ENCOURAGE_DIS_HI;
> + }
> +
> + writel(mask, pmu->base + mode);
> +
> + /*
> + * 2. Write SW encourage command sequence to the Software Encourage Reg (offset 0x44)
> + * SW turn-on command sequence: 0xff -> 0x05 -> 0x50
> + * SW turn-off command sequence: 0xff -> 0x0a -> 0xa0

I think you could replace the hard "coded" numbers here with a better
description idk without looking at the #defines above what these
correspond to. AFAICT, it'd be something like:
First write the ...ENCOURAGE_ON to reset the state machine which parses
the command sequence. It must be written every time.
Then write the lower bits of the command sequence, followed by the upper
bits. The sequence differs between powering on & off a domain.
> + *
> + * Note: writing SW_MODE_ENCOURAGE_ON (0xFF) to the SW_ENCOURAGE register,
> + * the purpose is to reset the state machine which is going to parse instruction
> + * sequence. It has to be written every time.
> + */
> + writel(JH71XX_PMU_SW_ENCOURAGE_ON, pmu->base + JH71XX_PMU_SW_ENCOURAGE);
> + writel(encourage_lo, pmu->base + JH71XX_PMU_SW_ENCOURAGE);
> + writel(encourage_hi, pmu->base + JH71XX_PMU_SW_ENCOURAGE);
> +
> + spin_unlock_irqrestore(&pmu->lock, flags);
> +
> + /* Wait for the power domain bit to be enabled / disabled */
> + if (on) {
> + ret = readl_poll_timeout_atomic(pmu->base + JH71XX_PMU_CURR_POWER_MODE,
> + val, val & mask,
> + 1, JH71XX_PMU_TIMEOUT_US);
> + } else {
> + ret = readl_poll_timeout_atomic(pmu->base + JH71XX_PMU_CURR_POWER_MODE,
> + val, !(val & mask),
> + 1, JH71XX_PMU_TIMEOUT_US);
> + }
> +
> + if (ret) {
> + dev_err(pmu->dev, "%s: failed to power %s\n",
> + pmd->genpd.name, on ? "on" : "off");
> + return -ETIMEDOUT;
> + }
> +
> + return 0;
> +}

> +static int jh71xx_pmu_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct device_node *np = dev->of_node;
> + const struct jh71xx_pmu_match_data *match_data;
> + struct jh71xx_pmu *pmu;
> + unsigned int i;
> + int ret;
> +
> + pmu = devm_kzalloc(dev, sizeof(*pmu), GFP_KERNEL);
> + if (!pmu)
> + return -ENOMEM;
> +
> + pmu->base = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(pmu->base))
> + return PTR_ERR(pmu->base);
> +
> + /* initialize pmu interrupt */

nit: this comment is ~pointless.

> + pmu->irq = platform_get_irq(pdev, 0);
> + if (pmu->irq < 0)
> + return pmu->irq;
> +
> + ret = devm_request_irq(dev, pmu->irq, jh71xx_pmu_interrupt,
> + 0, pdev->name, pmu);
> + if (ret)
> + dev_err(dev, "request irq failed.\n");

nit: s/request/requesting

Unfortunately I cannot really review the rest of this, but hopefully
I'll get a board soon and can try it out - or else send me a link to
your TRM or w/e.

Thanks,
Conor.

> +
> + match_data = of_device_get_match_data(dev);
> + if (!match_data)
> + return -EINVAL;
> +
> + pmu->genpd = devm_kcalloc(dev, match_data->num_domains,
> + sizeof(struct generic_pm_domain *),
> + GFP_KERNEL);
> + if (!pmu->genpd)
> + return -ENOMEM;
> +
> + pmu->dev = dev;
> + pmu->match_data = match_data;
> + pmu->genpd_data.domains = pmu->genpd;
> + pmu->genpd_data.num_domains = match_data->num_domains;
> +
> + for (i = 0; i < match_data->num_domains; i++) {
> + ret = jh71xx_pmu_init_domain(pmu, i);
> + if (ret) {
> + dev_err(dev, "failed to initialize power domain\n");
> + return ret;
> + }
> + }
> +
> + spin_lock_init(&pmu->lock);
> + jh71xx_pmu_int_enable(pmu, JH71XX_PMU_INT_ALL_MASK & ~JH71XX_PMU_INT_PCH_FAIL, true);
> +
> + ret = of_genpd_add_provider_onecell(np, &pmu->genpd_data);
> + if (ret) {
> + dev_err(dev, "failed to register genpd driver: %d\n", ret);
> + return ret;
> + }
> +
> + dev_info(dev, "registered %u power domains\n", i);
> +
> + return 0;
> +}
> +
> +static const struct jh71xx_domain_info jh7110_power_domains[] = {
> + [JH7110_PD_SYSTOP] = {
> + .name = "SYSTOP",
> + .bit = 0,
> + .flags = GENPD_FLAG_ALWAYS_ON,
> + },
> + [JH7110_PD_CPU] = {
> + .name = "CPU",
> + .bit = 1,
> + .flags = GENPD_FLAG_ALWAYS_ON,
> + },
> + [JH7110_PD_GPUA] = {
> + .name = "GPUA",
> + .bit = 2,
> + },
> + [JH7110_PD_VDEC] = {
> + .name = "VDEC",
> + .bit = 3,
> + },
> + [JH7110_PD_VOUT] = {
> + .name = "VOUT",
> + .bit = 4,
> + },
> + [JH7110_PD_ISP] = {
> + .name = "ISP",
> + .bit = 5,
> + },
> + [JH7110_PD_VENC] = {
> + .name = "VENC",
> + .bit = 6,
> + },
> +};
> +
> +static const struct jh71xx_pmu_match_data jh7110_pmu = {
> + .num_domains = ARRAY_SIZE(jh7110_power_domains),
> + .domain_info = jh7110_power_domains,
> +};
> +
> +static const struct of_device_id jh71xx_pmu_of_match[] = {
> + {
> + .compatible = "starfive,jh7110-pmu",
> + .data = (void *)&jh7110_pmu,
> + }, {
> + /* sentinel */
> + }
> +};
> +
> +static struct platform_driver jh71xx_pmu_driver = {
> + .driver = {
> + .name = "jh71xx-pmu",
> + .of_match_table = jh71xx_pmu_of_match,
> + },
> + .probe = jh71xx_pmu_probe,
> +};
> +builtin_platform_driver(jh71xx_pmu_driver);
> +
> +MODULE_AUTHOR("Walker Chen <walker.chen@xxxxxxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("StarFive JH71XX PMU Driver");
> +MODULE_LICENSE("GPL");
> --
> 2.17.1
>
>

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