Re: [PATCH v3 5/7] soc: mediatek: apu: Add apusys and add apu power domain driver

AngeloGioacchino Del Regno
2021-10-26T09:57:46Z

Il 23/10/21 12:13, Flora Fu ha scritto:
> Add the apusys in soc.
> Add driver for apu power domains.
> APU power domain shall be enabled before accessing the
> internal sub modules.
>
> Signed-off-by: Flora Fu <flora.fu@mediatek.com>

Hello,
thanks for the patch! However, there are a few things to improve...

> ---
> drivers/soc/mediatek/Kconfig | 19 +
> drivers/soc/mediatek/Makefile | 1 +
> drivers/soc/mediatek/apusys/Makefile | 2 +
> drivers/soc/mediatek/apusys/mtk-apu-pm.c | 633 +++++++++++++++++++++++
> 4 files changed, 655 insertions(+)
> create mode 100644 drivers/soc/mediatek/apusys/Makefile
> create mode 100644 drivers/soc/mediatek/apusys/mtk-apu-pm.c
>
> diff --git a/drivers/soc/mediatek/Kconfig b/drivers/soc/mediatek/Kconfig
> index fdd8bc08569e..d9bac2710494 100644
> --- a/drivers/soc/mediatek/Kconfig
> +++ b/drivers/soc/mediatek/Kconfig
> @@ -5,6 +5,25 @@
> menu "MediaTek SoC drivers"
> depends on ARCH_MEDIATEK || COMPILE_TEST
>
> +config MTK_APUSYS
> + bool "MediaTek APUSYS Support"
> + select REGMAP
> + help
> + Say yes here to add support for the MediaTek AI Processing Unit
> + Subsystem (APUSYS).
> + The APUSYS is a proprietary hardware in SoC to support AI
> + operations.
> +

If these config entries are for files in subfolder apusys/, then you should move

them to drivers/soc/mediatek/apusys/Kconfig and make sure that said Kconfig will

contain a "if MTK_APUSYS" as to include the subconfigs only if the parent one is

declared =y.

> +config MTK_APU_PM
> + bool "MediaTek APU power management support"

Can we use tristate here? This doesn't look like being a boot-critical driver,
so it can as well be loaded after rootfs init.
Permitting to compile this as a module will also shrink the kernel image size
and that's important when you build a generic kernel image, and that's for both
the MediaTek SoCs case (older SoCs don't need this driver) and for others.

> + select REGMAP
> + select PM_GENERIC_DOMAINS if PM
> + help
> + Say yes here to add support for power management control
> + to Mediatek AI Processing Unit Subsystem (APUSYS).
> + APU power domain shall be enabled before accessing the
> + internal sub modules.
> +
> config MTK_CMDQ
> tristate "MediaTek CMDQ Support"
> depends on ARCH_MEDIATEK || COMPILE_TEST
> diff --git a/drivers/soc/mediatek/Makefile b/drivers/soc/mediatek/Makefile
> index 90270f8114ed..e46e7a3c21e7 100644
> --- a/drivers/soc/mediatek/Makefile
> +++ b/drivers/soc/mediatek/Makefile
> @@ -1,4 +1,5 @@
> # SPDX-License-Identifier: GPL-2.0-only
> +obj-$(CONFIG_MTK_APUSYS) += apusys/
> obj-$(CONFIG_MTK_CMDQ) += mtk-cmdq-helper.o
> obj-$(CONFIG_MTK_DEVAPC) += mtk-devapc.o
> obj-$(CONFIG_MTK_INFRACFG) += mtk-infracfg.o
> diff --git a/drivers/soc/mediatek/apusys/Makefile b/drivers/soc/mediatek/apusys/Makefile
> new file mode 100644
> index 000000000000..8821c0f0b7b7
> --- /dev/null
> +++ b/drivers/soc/mediatek/apusys/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0
> +obj-$(CONFIG_MTK_APU_PM) += mtk-apu-pm.o
> diff --git a/drivers/soc/mediatek/apusys/mtk-apu-pm.c b/drivers/soc/mediatek/apusys/mtk-apu-pm.c
> new file mode 100644
> index 000000000000..828aa9eb6b37
> --- /dev/null
> +++ b/drivers/soc/mediatek/apusys/mtk-apu-pm.c
> @@ -0,0 +1,633 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2021 MediaTek Inc.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_clk.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_domain.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +
> +#define APU_PD_IPUIF_HW_CG BIT(0)
> +#define APU_PD_RPC_AUTO_BUCK BIT(1)
> +#define APU_PD_CAPS(_pd, _x) ((_pd)->data->caps & (_x))
> +
> +#define MTK_POLL_DELAY_US 10
> +#define MTK_POLL_TIMEOUT USEC_PER_SEC
> +
> +/* rpc_top_con*/
> +#define SLEEP_REQ BIT(0)
> +#define APU_BUCK_ELS_EN BIT(3)
> +
> +/*conn_clr, conn1_clr, vcore_clr */
> +#define CG_CLR (0xFFFFFFFF)
> +
> +/* mt8192 rpc_sw_type */
> +#define MT8192_RPC_SW_TYPE0 (0x200)
> +#define MT8192_RPC_SW_TYPE1 (0x210)
> +#define MT8192_RPC_SW_TYPE2 (0x220)
> +#define MT8192_RPC_SW_TYPE3 (0x230)
> +#define MT8192_RPC_SW_TYPE4 (0x240)
> +#define MT8192_RPC_SW_TYPE6 (0x260)
> +#define MT8192_RPC_SW_TYPE7 (0x270)

What about...

/* mt8192 rpc_sw_type (0..7) */
#define MT8192_RPC_SW_TYPE(x) (0x200 + (x * 0x10))

> +
> +/* rpc_sw_type*/
> +static const struct reg_sequence mt8192_rpc_sw_type[] = {
> + { MT8192_RPC_SW_TYPE0, 0xFF },
> + { MT8192_RPC_SW_TYPE2, 0x7 },
> + { MT8192_RPC_SW_TYPE3, 0x7 },
> + { MT8192_RPC_SW_TYPE6, 0x3 },
> +};
> +
> +struct apu_top_domain {
> + u32 spm_ext_buck_iso;
> + u32 spm_ext_buck_iso_mask;
> + u32 spm_cross_wake_m01;
> + u32 wake_apu;
> + u32 spm_other_pwr;
> + u32 pwr_status;
> + u32 conn_clr;
> + u32 conn1_clr;
> + u32 vcore_clr;
> + u32 rpc_top_con;
> + u32 rpc_top_con_init_mask;
> + u32 rpc_top_sel;
> + u32 rpc_top_intf_pwr_rdy;
> + u32 pwr_rdy;
> + const struct reg_sequence *rpc_sw_type;
> + int rpc_sw_ntype;

For the sake of clarity and readability, I would name this one num_rpc_sw_type
or num_rpc_sw, which also keeps naming consistency across this file, since later
in this file, you're doing the same with domains_data.

> +};
> +
> +static struct apu_top_domain mt8192_top_reg = {
> + .spm_ext_buck_iso = 0x39C,
> + .spm_ext_buck_iso_mask = 0x21,
> + .spm_cross_wake_m01 = 0x670,
> + .wake_apu = BIT(0),
> + .spm_other_pwr = 0x178,
> + .pwr_status = BIT(5),
> + .conn_clr = 0x008,

Please drop leading zeroes. 0x8 here.

> + .vcore_clr = 0x008,

0x8

> + .rpc_top_con = 0x000,

0

> + .rpc_top_con_init_mask = 0x49E,
> + .rpc_top_sel = 0x004,

0x4

> + .rpc_top_intf_pwr_rdy = 0x044,

0x44

> + .pwr_rdy = BIT(0),
> + .rpc_sw_type = mt8192_rpc_sw_type,
> + .rpc_sw_ntype = ARRAY_SIZE(mt8192_rpc_sw_type),
> +};
> +
> +struct apusys {
> + struct device *dev;
> + struct regmap *scpsys;
> + struct regmap *conn;
> + struct regmap *conn1;
> + struct regmap *vcore;
> + struct regmap *rpc;
> + struct regulator *vsram_supply;
> + const struct apu_pm_data *data;
> + struct genpd_onecell_data pd_data;
> + struct generic_pm_domain *domains[];
> +};
> +
> +struct apu_domain {
> + struct generic_pm_domain genpd;
> + const struct apu_domain_data *data;
> + struct apusys *apusys;
> + struct regulator *domain_supply;
> + int num_clks;
> + struct clk_bulk_data *clks;
> + struct clk *clk_top_conn;
> + struct clk *clk_top_ipu_if;
> + struct clk *clk_off;
> + struct clk *clk_on_def;
> +};
> +
> +struct apu_domain_data {
> + int domain_idx;
> + char *name;
> + struct apu_top_domain *topd;
> + u8 caps;
> +};
> +
> +struct apu_pm_data {
> + const struct apu_domain_data *domains_data;
> + int num_domains;
> +};
> +
> +#define to_apu_domain(gpd) container_of(gpd, struct apu_domain, genpd)
> +
> +static int apu_top_init_hw(struct apu_domain *pd)
> +{
> + struct apusys *apusys = pd->apusys;
> + int ret;
> +
> + /*
> + * set memory type to PD or sleep group
> + * sw_type register for each memory group, set to PD mode default
> + */
> + if (pd->data->topd->rpc_sw_ntype) {
> + ret = regmap_register_patch(apusys->rpc,
> + pd->data->topd->rpc_sw_type,
> + pd->data->topd->rpc_sw_ntype);
> + if (ret < 0) {
> + dev_err(apusys->dev, "Failed to rpc patch: %d\n", ret);
> + return ret;
> + }
> + }
> +
> + /* mask RPC IRQ and bypass WFI */
> + regmap_set_bits(apusys->rpc, pd->data->topd->rpc_top_sel,
> + pd->data->topd->rpc_top_con_init_mask);

This function may return a failure.. and this is not a performance-critical case,
nor a case in which it's 100% granted that this won't fail: you're calling this
at initialization phase (when you're adding the domain), so if there's anything
that would make this fail, this is definitely the right place to check for that.

Please check the return value.

> +
> + if (APU_PD_CAPS(pd, APU_PD_RPC_AUTO_BUCK))
> + regmap_set_bits(apusys->rpc,
> + pd->data->topd->rpc_top_con, APU_BUCK_ELS_EN);
> +
> + return 0;
> +}
> +
> +static const struct apu_domain_data apu_domain_data_mt8192[] = {
> + {
> + .domain_idx = 0,
> + .name = "apu-top",
> + .caps = APU_PD_IPUIF_HW_CG,
> + .topd = &mt8192_top_reg,
> + }
> +};
> +
> +static const struct apu_pm_data mt8192_apu_pm_data = {
> + .domains_data = apu_domain_data_mt8192,
> + .num_domains = ARRAY_SIZE(apu_domain_data_mt8192),
> +};
> +
> +static int apu_top_power_on(struct generic_pm_domain *genpd)
> +{
> + struct apu_domain *pd = to_apu_domain(genpd);
> + struct apusys *apusys = pd->apusys;
> + int ret, tmp;
> +
> + if (apusys->vsram_supply) {
> + ret = regulator_enable(apusys->vsram_supply);
> + if (ret < 0)
> + return ret;
> + }
> +
> + if (pd->domain_supply) {
> + ret = regulator_enable(pd->domain_supply);
> + if (ret < 0)
> + goto err_regulator;
> + }
> +
> + regmap_clear_bits(apusys->scpsys, pd->data->topd->spm_ext_buck_iso,
> + pd->data->topd->spm_ext_buck_iso_mask);
> +
> + regmap_set_bits(apusys->rpc, pd->data->topd->rpc_top_sel,
> + pd->data->topd->rpc_top_con_init_mask);
> +
> + if (APU_PD_CAPS(pd, APU_PD_IPUIF_HW_CG)) {
> + ret = clk_prepare_enable(pd->clk_top_conn);
> + if (ret) {
> + dev_err(apusys->dev, "Failed enable top_conn clk\n");
> + goto err_clk;
> + }
> +
> + ret = clk_set_parent(pd->clk_top_ipu_if, pd->clk_on_def);
> + if (ret) {
> + dev_err(apusys->dev, "Failed set ipu_if mux\n");
> + goto err_clk;
> + }
> +
> + /* The ipu_if clock is gatting by HW. Only enable once. */

typo: gating

> + if (!__clk_is_enabled(pd->clk_top_ipu_if)) {
> + ret = clk_prepare_enable(pd->clk_top_ipu_if);
> + if (ret) {
> + dev_err(apusys->dev, "Failed enable ipu_if\n");
> + goto err_clk;
> + }
> + }
> + } else {
> + ret = clk_bulk_prepare_enable(pd->num_clks, pd->clks);
> + if (ret)
> + goto err_clk;
> + }
> +
> + regmap_set_bits(apusys->scpsys,
> + pd->data->topd->spm_cross_wake_m01,
> + pd->data->topd->wake_apu);
> +
> + ret = regmap_read_poll_timeout(apusys->scpsys,
> + pd->data->topd->spm_other_pwr,
> + tmp,
> + (tmp & pd->data->topd->pwr_status) ==
> + pd->data->topd->pwr_status,
> + MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
> + if (ret < 0) {
> + dev_err(apusys->dev, "apu top on wait SPM PWR_ACK != 0\n");
> + goto err_clk;
> + }
> +
> + ret = regmap_read_poll_timeout(apusys->rpc,
> + pd->data->topd->rpc_top_intf_pwr_rdy,
> + tmp, (tmp & pd->data->topd->pwr_rdy) ==
> + pd->data->topd->pwr_rdy,
> + MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
> + if (ret < 0) {
> + dev_err(apusys->dev, "apu top on wait RPC PWR_RDY != 0\n");
> + goto err_clk;
> + }
> +
> + if (apusys->vcore)
> + regmap_write(apusys->vcore, pd->data->topd->vcore_clr, CG_CLR);
> +
> + if (apusys->conn)
> + regmap_write(apusys->conn, pd->data->topd->conn_clr, CG_CLR);
> +
> + if (apusys->conn1)
> + regmap_write(apusys->conn1, pd->data->topd->conn1_clr, CG_CLR);
> +
> + return 0;
> +
> +err_clk:
> + if (APU_PD_CAPS(pd, APU_PD_IPUIF_HW_CG)) {
> + clk_disable_unprepare(pd->clk_top_conn);
> + clk_disable_unprepare(pd->clk_top_ipu_if);
> + } else {
> + clk_bulk_disable_unprepare(pd->num_clks, pd->clks);
> + }
> + if (pd->domain_supply)
> + ret = regulator_disable(pd->domain_supply);
> +err_regulator:
> + if (apusys->vsram_supply)
> + ret = regulator_disable(apusys->vsram_supply);
> +
> + return ret;
> +}
> +
> +static int apu_top_power_off(struct generic_pm_domain *genpd)
> +{
> + struct apu_domain *pd = to_apu_domain(genpd);
> + struct apusys *apusys = pd->apusys;
> + int ret, tmp;
> +
> + if (apusys->vcore)
> + regmap_write(apusys->vcore, pd->data->topd->vcore_clr, CG_CLR);
> +
> + if (apusys->conn)
> + regmap_write(apusys->conn, pd->data->topd->conn_clr, CG_CLR);
> +
> + if (apusys->conn1)
> + regmap_write(apusys->conn1, pd->data->topd->conn1_clr, CG_CLR);
> +
> + regmap_clear_bits(apusys->scpsys,
> + pd->data->topd->spm_cross_wake_m01,
> + pd->data->topd->wake_apu);
> +
> + regmap_set_bits(apusys->rpc, pd->data->topd->rpc_top_con, SLEEP_REQ);
> +
> + ret = regmap_read_poll_timeout(apusys->rpc,
> + pd->data->topd->rpc_top_intf_pwr_rdy,
> + tmp,
> + (tmp & pd->data->topd->pwr_rdy) == 0x0,
> + MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
> + if (ret < 0) {
> + dev_err(apusys->dev, "apu top off wait RPC PWR_RDY != 0\n");
> + return ret;
> + }
> +
> + ret = regmap_read_poll_timeout(apusys->scpsys,
> + pd->data->topd->spm_other_pwr, tmp,
> + (tmp & pd->data->topd->pwr_status) == 0x0,
> + MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
> + if (ret < 0) {
> + dev_err(apusys->dev, "apu top off wait SPM PWR_ACK != 0\n");
> + return ret;
> + }
> +
> + if (APU_PD_CAPS(pd, APU_PD_IPUIF_HW_CG)) {
> + clk_disable_unprepare(pd->clk_top_conn);
> + ret = clk_set_parent(pd->clk_top_ipu_if, pd->clk_off);
> + if (ret) {
> + dev_err(apusys->dev, "Failed set ipu_if rate\n");
> + return ret;
> + }
> + } else {
> + clk_bulk_disable_unprepare(pd->num_clks, pd->clks);
> + }
> +
> + regmap_set_bits(apusys->scpsys,
> + pd->data->topd->spm_ext_buck_iso,
> + pd->data->topd->spm_ext_buck_iso_mask);
> +
> + if (apusys->vsram_supply) {
> + ret = regulator_disable(apusys->vsram_supply);
> + if (ret < 0)
> + return ret;
> + }
> +
> + if (pd->domain_supply) {
> + ret = regulator_disable(pd->domain_supply);
> + if (ret < 0)
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static struct generic_pm_domain *apu_add_one_domain(struct apusys *apusys,
> + struct device_node *node)
> +{
> + const struct apu_domain_data *domain_data;
> + struct apu_domain *pd;
> + int ret;
> + u32 id;
> + int i;
> + struct clk *clk;
> +
> + ret = of_property_read_u32(node, "reg", &id);
> + if (ret) {
> + dev_dbg(apusys->dev, "%pOF: invalid reg: %d\n", node, ret);
> + return ERR_PTR(-EINVAL);

Just use the error value in 'ret', instead of forcing -EINVAL here.

> + }
> +
> + if (id >= apusys->data->num_domains) {
> + dev_dbg(apusys->dev, "%pOF: invalid id %d\n", node, id);
> + return ERR_PTR(-EINVAL);
> + }
> +
> + domain_data = &apusys->data->domains_data[id];
> +
> + pd = devm_kzalloc(apusys->dev, sizeof(*pd), GFP_KERNEL);
> + if (!pd)
> + return ERR_PTR(-ENOMEM);
> +
> + pd->data = domain_data;
> + pd->apusys = apusys;
> +
> + pd->domain_supply = devm_regulator_get_optional(apusys->dev, "domain");

This may return -EPROBE_DEFER: in that case, you don't want to ignore the supply,
but defer probing this driver until said supply becomes available so, if that
happens, you should return.

> + if (IS_ERR(pd->domain_supply))
> + pd->domain_supply = NULL;
> +
> + /*
> + * For HW using ipu_if, the clock is switched to 26M
> + * when power down top domain and switch to default clock rate
> + * before power on.
> + */
> + if (APU_PD_CAPS(pd, APU_PD_IPUIF_HW_CG)) {
> + pd->clk_top_conn = of_clk_get_by_name(node, "clk_top_conn");
> + if (IS_ERR(pd->clk_top_conn)) {
> + dev_err(apusys->dev, "Fail to get clk_top_conn clock\n");
> + ret = PTR_ERR(pd->clk_top_conn);
> + goto err_put_clocks;
> + }
> +
> + pd->clk_top_ipu_if = of_clk_get_by_name(node, "clk_top_ipu_if");
> + if (IS_ERR(pd->clk_top_ipu_if)) {
> + dev_err(apusys->dev, "Fail to get clk_top_ipu_if clock\n");
> + ret = PTR_ERR(pd->clk_top_ipu_if);
> + goto err_put_clocks;
> + }
> +
> + pd->clk_off = of_clk_get_by_name(node, "clk_off");
> + if (IS_ERR(pd->clk_off)) {
> + dev_err(apusys->dev, "Fail to get clk_off clock\n");
> + ret = PTR_ERR(pd->clk_off);
> + goto err_put_clocks;
> + }
> +
> + pd->clk_on_def = of_clk_get_by_name(node, "clk_on_default");
> + if (IS_ERR(pd->clk_on_def)) {
> + dev_err(apusys->dev, "Fail to get clk_on_default clock\n");
> + ret = PTR_ERR(pd->clk_on_def);
> + goto err_put_clocks;
> + }
> + } else {
> + pd->num_clks = of_clk_get_parent_count(node);
> + if (pd->num_clks > 0) {
> + pd->clks = devm_kcalloc(apusys->dev, pd->num_clks,
> + sizeof(*pd->clks), GFP_KERNEL);
> + if (!pd->clks)
> + return ERR_PTR(-ENOMEM);
> + }
> +
> + for (i = 0; i < pd->num_clks; i++) {
> + clk = of_clk_get(node, i);
> + if (IS_ERR(clk)) {
> + ret = PTR_ERR(clk);
> + dev_dbg(apusys->dev,
> + "%pOF: failed to get clk at index %d: %d\n",
> + node, i, ret);
> + goto err_put_clocks;
> + }
> + pd->clks[i].clk = clk;
> + }
> + }
> +
> + if (apusys->domains[id]) {
> + ret = -EINVAL;

Error: X already exists -> -EEXIST

> + dev_err(apusys->dev, "domain id %d already exists\n", id);
> + goto err_put_clocks;
> + }
> +
> + /* set rpc hw init status */
> + ret = apu_top_init_hw(pd);
> + if (ret < 0) {
> + dev_dbg(apusys->dev, "top init fail ret = %d\n", ret);
> + goto err_put_clocks;
> + }
> +
> + if (!pd->data->name)
> + pd->genpd.name = node->name;
> + else
> + pd->genpd.name = pd->data->name;
> + pd->genpd.power_off = apu_top_power_off;
> + pd->genpd.power_on = apu_top_power_on;
> +
> + /*
> + * Initially turn on all domains to make the domains usable
> + * with !CONFIG_PM and to get the hardware in sync with the
> + * software. The unused domains will be switched off during
> + * late_init time.
> + */
> + ret = pd->genpd.power_on(&pd->genpd);
> + if (ret < 0) {
> + dev_dbg(apusys->dev, "%pOF: power on domain fail: %d\n",
> + node, ret);
> + goto err_put_clocks;
> + }
> +
> + pm_genpd_init(&pd->genpd, NULL, false);

This function may return failure: please check the return value.

> +
> + apusys->domains[id] = &pd->genpd;
> +
> + return apusys->pd_data.domains[id];
> +
> +err_put_clocks:
> + if (APU_PD_CAPS(pd, APU_PD_IPUIF_HW_CG)) {
> + clk_put(pd->clk_top_conn);
> + clk_put(pd->clk_top_ipu_if);
> + clk_put(pd->clk_off);
> + clk_put(pd->clk_on_def);
> + } else {
> + clk_bulk_put(pd->num_clks, pd->clks);
> + }
> + return ERR_PTR(ret);
> +}
> +
> +static void apu_remove_one_domain(struct apu_domain *pd)
> +{
> + int ret;
> +
> + if (pd->genpd.power_off)
> + pd->genpd.power_off(&pd->genpd);
> +
> + /*
> + * We're in the error cleanup already, so we only complain,
> + * but won't emit another error on top of the original one.
> + */
> + ret = pm_genpd_remove(&pd->genpd);
> + if (ret < 0)
> + dev_dbg(pd->apusys->dev,
> + "Remove domain '%s' : %d - state may be inconsistent\n",
> + pd->genpd.name, ret);
> +
> + if (APU_PD_CAPS(pd, APU_PD_IPUIF_HW_CG)) {
> + clk_put(pd->clk_top_conn);
> + clk_put(pd->clk_top_ipu_if);
> + clk_put(pd->clk_off);
> + clk_put(pd->clk_on_def);
> + } else {
> + clk_bulk_put(pd->num_clks, pd->clks);
> + }
> +}
> +
> +static void apu_domain_cleanup(struct apusys *apusys)
> +{
> + struct generic_pm_domain *genpd;
> + struct apu_domain *pd;
> + int i;
> +
> + for (i = apusys->pd_data.num_domains - 1; i >= 0; i--) {
> + genpd = apusys->pd_data.domains[i];
> + if (genpd) {
> + pd = to_apu_domain(genpd);
> + apu_remove_one_domain(pd);
> + }
> + }
> +}
> +
> +static const struct of_device_id apu_pm_of_match[] = {
> + {
> + .compatible = "mediatek,mt8192-apu-pm",
> + .data = &mt8192_apu_pm_data,
> + },
> + { }
> +};
> +
> +static int apu_pm_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct device_node *np = dev->of_node;
> + const struct apu_pm_data *data;
> + struct device_node *node;
> + struct apusys *apusys;
> + int ret;
> +
> + data = of_device_get_match_data(&pdev->dev);
> + if (!data) {
> + dev_dbg(dev, "no power domain data\n");
> + return -EINVAL;
> + }
> +
> + apusys = devm_kzalloc(dev,
> + struct_size(apusys, domains, data->num_domains),
> + GFP_KERNEL);
> + if (!apusys)
> + return -ENOMEM;
> +
> + apusys->dev = dev;
> + apusys->data = data;
> + apusys->pd_data.domains = apusys->domains;
> + apusys->pd_data.num_domains = data->num_domains;
> +
> + apusys->vsram_supply = devm_regulator_get_optional(dev, "vsram");
> + if (IS_ERR(apusys->vsram_supply)) {
> + ret = PTR_ERR(apusys->vsram_supply);
> + if (ret != -EPROBE_DEFER) {
> + dev_err(dev, "vsram_supply fail, ret=%d", ret);
> + apusys->vsram_supply = NULL;
> + }
> + return ret;
> + }
> +
> + /* rpc */
> + apusys->rpc = syscon_node_to_regmap(np);
> + if (IS_ERR(apusys->rpc)) {
> + dev_err(dev, "Unable to get rpc\n");
> + return PTR_ERR(apusys->rpc);
> + }
> +
> + /* scpsys */
> + apusys->scpsys = syscon_regmap_lookup_by_phandle(np, "mediatek,scpsys");
> + if (IS_ERR(apusys->scpsys)) {
> + dev_err(dev, "Unable to get scpsys\n");
> + return PTR_ERR(apusys->scpsys);
> + }
> +
> + /* apusys conn */
> + apusys->conn = syscon_regmap_lookup_by_phandle_optional(np, "mediatek,apu-conn");
> + if (IS_ERR(apusys->conn))
> + dev_info(dev, "No optional phandle apu-conn\n");

I take it as if some platforms may be expected to not have any optional phandle
for that (and for the others): in such case, this would result in being a useless
message. Please use dev_dbg() here.

> +
> + /* apusys conn1 */
> + apusys->conn1 = syscon_regmap_lookup_by_phandle_optional(np, "mediatek,apu-conn1");
> + if (IS_ERR(apusys->conn1))
> + dev_info(dev, "No optional phandle apu-conn1\n");
> +
> + /* apusys vcore */
> + apusys->vcore = syscon_regmap_lookup_by_phandle_optional(np, "mediatek,apu-vcore");
> + if (IS_ERR(apusys->vcore))
> + dev_info(dev, "No optional phandle apu-vcore\n");
> +
> + for_each_available_child_of_node(np, node) {
> + struct generic_pm_domain *domain;
> +
> + domain = apu_add_one_domain(apusys, node);
> + if (IS_ERR(domain)) {
> + ret = PTR_ERR(domain);
> + of_node_put(node);
> + goto err_cleanup_domains;
> + }
> + }
> +
> + ret = of_genpd_add_provider_onecell(np, &apusys->pd_data);
> + if (ret) {
> + dev_dbg(dev, "failed to add provider: %d\n", ret);
> + goto err_cleanup_domains;
> + }
> +
> + return 0;
> +
> +err_cleanup_domains:
> + apu_domain_cleanup(apusys);
> + return ret;
> +}
> +
> +static struct platform_driver apu_pm_driver = {
> + .probe = apu_pm_probe,

In this driver, you already have the means to remove the domains and cleanup the
state... it would probably be trivial to add a .remove handler.

What do you think about that?
Also, is there be any reason for which removing this driver during runtime
would be unsafe?

In my opinion, it would be beneficial to have a remove handler also in the
development usecase, as you'd be able to just recompile this module, remove and
reinsert it to test new changes, without the need of copying an entire new
kernel image and rebooting the device.

> + .driver = {
> + .name = "mtk-apu-pm",
> + .suppress_bind_attrs = true,
> + .of_match_table = apu_pm_of_match,
> + },
> +};
> +builtin_platform_driver(apu_pm_driver);
>

MODULE_LICENSE() is missing! Please add it.
Also, as said in the Kconfig comment, this driver can probably be a module, in
which case... module_platform_driver(apu_pm_driver);

Thanks,
- Angelo