diff mbox

[v5,2/3] soc/imx: Add GPCv2 power gating driver

Message ID 20170314150540.27831-3-andrew.smirnov@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Andrey Smirnov March 14, 2017, 3:05 p.m. UTC 
Add code allowing for control of various power domains managed by GPCv2
IP block found in i.MX7 series of SoCs. Power domains covered by this
patch are:

    - PCIE PHY
    - MIPI PHY
    - USB HSIC PHY
    - USB OTG1/2 PHY

Support for any other power domain controlled by GPC is not present, and
can be added at some later point.

Testing of this code was done against a PCIe driver.

Cc: yurovsky@gmail.com
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---
 drivers/soc/Kconfig      |   1 +
 drivers/soc/imx/Kconfig  |   9 ++
 drivers/soc/imx/Makefile |   1 +
 drivers/soc/imx/gpcv2.c  | 387 +++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 398 insertions(+)
 create mode 100644 drivers/soc/imx/Kconfig
 create mode 100644 drivers/soc/imx/gpcv2.c

Comments

Shawn Guo March 16, 2017, 3:40 a.m. UTC | #1 
On Tue, Mar 14, 2017 at 08:05:39AM -0700, Andrey Smirnov wrote:
> Add code allowing for control of various power domains managed by GPCv2
> IP block found in i.MX7 series of SoCs. Power domains covered by this
> patch are:
> 
>     - PCIE PHY
>     - MIPI PHY
>     - USB HSIC PHY
>     - USB OTG1/2 PHY
> 
> Support for any other power domain controlled by GPC is not present, and
> can be added at some later point.
> 
> Testing of this code was done against a PCIe driver.
> 
> Cc: yurovsky@gmail.com
> Cc: Lucas Stach <l.stach@pengutronix.de>
> Cc: Fabio Estevam <fabio.estevam@nxp.com>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> ---
>  drivers/soc/Kconfig      |   1 +
>  drivers/soc/imx/Kconfig  |   9 ++
>  drivers/soc/imx/Makefile |   1 +
>  drivers/soc/imx/gpcv2.c  | 387 +++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 398 insertions(+)
>  create mode 100644 drivers/soc/imx/Kconfig
>  create mode 100644 drivers/soc/imx/gpcv2.c
> 
> diff --git a/drivers/soc/Kconfig b/drivers/soc/Kconfig
> index f31bceb..55a4eb8 100644
> --- a/drivers/soc/Kconfig
> +++ b/drivers/soc/Kconfig
> @@ -2,6 +2,7 @@ menu "SOC (System On Chip) specific Drivers"
>  
>  source "drivers/soc/bcm/Kconfig"
>  source "drivers/soc/fsl/Kconfig"
> +source "drivers/soc/imx/Kconfig"
>  source "drivers/soc/mediatek/Kconfig"
>  source "drivers/soc/qcom/Kconfig"
>  source "drivers/soc/rockchip/Kconfig"
> diff --git a/drivers/soc/imx/Kconfig b/drivers/soc/imx/Kconfig
> new file mode 100644
> index 0000000..9c84eb0
> --- /dev/null
> +++ b/drivers/soc/imx/Kconfig
> @@ -0,0 +1,9 @@
> +menu "i.MX SoC drivers"
> +
> +config IMX7_PM_DOMAINS
> +	bool "i.MX7 PM domains"
> +	select PM_GENERIC_DOMAINS
> +	depends on SOC_IMX7D || (COMPILE_TEST && OF)

Can we do something like below to save the patch #3?

	default y if SOC_IMX7D

> +
> +endmenu
> +
> diff --git a/drivers/soc/imx/Makefile b/drivers/soc/imx/Makefile
> index 35861f5..5b6e396 100644
> --- a/drivers/soc/imx/Makefile
> +++ b/drivers/soc/imx/Makefile
> @@ -1 +1,2 @@
>  obj-y += gpc.o
> +obj-$(CONFIG_IMX7_PM_DOMAINS) += gpcv2.o
> diff --git a/drivers/soc/imx/gpcv2.c b/drivers/soc/imx/gpcv2.c
> new file mode 100644
> index 0000000..7d52141
> --- /dev/null
> +++ b/drivers/soc/imx/gpcv2.c
> @@ -0,0 +1,387 @@
> +/*
> + * Copyright 2017 Impinj, Inc
> + * Author: Andrey Smirnov <andrew.smirnov@gmail.com>
> + *
> + * Based on the code of analogus driver:
> + *
> + * Copyright 2015-2017 Pengutronix, Lucas Stach <kernel@pengutronix.de>
> + *
> + * The code contained herein is licensed under the GNU General Public
> + * License. You may obtain a copy of the GNU General Public License
> + * Version 2 or later at the following locations:
> + *
> + * http://www.opensource.org/licenses/gpl-license.html
> + * http://www.gnu.org/copyleft/gpl.html
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/io.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>
> +#include <dt-bindings/power/imx7-power.h>
> +
> +#define GPC_PGC_CPU_MAPPING	0xec
> +#define USB_HSIC_PHY_A7_DOMAIN	BIT(6)
> +#define USB_OTG2_PHY_A7_DOMAIN	BIT(5)
> +#define USB_OTG1_PHY_A7_DOMAIN	BIT(4)
> +#define PCIE_PHY_A7_DOMAIN	BIT(3)
> +#define MIPI_PHY_A7_DOMAIN	BIT(2)
> +
> +#define GPC_PU_PGC_SW_PUP_REQ	0xf8
> +#define GPC_PU_PGC_SW_PDN_REQ	0x104
> +#define USB_HSIC_PHY_SW_Pxx_REQ	BIT(4)
> +#define USB_OTG2_PHY_SW_Pxx_REQ	BIT(3)
> +#define USB_OTG1_PHY_SW_Pxx_REQ	BIT(2)
> +#define PCIE_PHY_SW_Pxx_REQ	BIT(1)
> +#define MIPI_PHY_SW_Pxx_REQ	BIT(0)
> +
> +#define GPC_MAX_REGISTER	0x1000
> +
> +#define GPC_PGC_nCTRL_PCR	BIT(0)
> +
> +struct imx7_pgc_domain {
> +	struct generic_pm_domain genpd;
> +	struct regmap *regmap;
> +	struct regulator *regulator;
> +
> +	unsigned int pgc_nctrl;
> +
> +	const struct {
> +		u32 pxx;
> +		u32 map;
> +	} bits;
> +
> +	const int voltage;
> +	struct device *dev;
> +};
> +
> +static int imx7_gpc_pu_pgc_sw_pxx_req(struct generic_pm_domain *genpd,
> +				      bool on)
> +{
> +	int ret = 0;
> +	unsigned long deadline;
> +	struct imx7_pgc_domain *domain = container_of(genpd,
> +						      struct imx7_pgc_domain,
> +						      genpd);
> +	unsigned int offset = on ?
> +		GPC_PU_PGC_SW_PUP_REQ : GPC_PU_PGC_SW_PDN_REQ;
> +
> +	const bool enable_power_control = domain->pgc_nctrl && !on;
> +	const bool has_regulator = !IS_ERR(domain->regulator);

Again, reverse tree for variable declaration section, and drop the
newline in middle of it please.

Shawn

> +
> +	regmap_update_bits(domain->regmap, GPC_PGC_CPU_MAPPING,
> +			   domain->bits.map, domain->bits.map);
> +
> +	if (has_regulator && on) {
> +		ret = regulator_enable(domain->regulator);
> +		if (ret) {
> +			dev_err(domain->dev, "failed to enable regulator\n");
> +			goto unmap;
> +		}
> +	}
> +
> +	if (enable_power_control)
> +		regmap_update_bits(domain->regmap, domain->pgc_nctrl,
> +				   GPC_PGC_nCTRL_PCR, GPC_PGC_nCTRL_PCR);
> +
> +	regmap_update_bits(domain->regmap, offset,
> +			   domain->bits.pxx, domain->bits.pxx);
> +
> +	/*
> +	 * As per "5.5.9.4 Example Code 4" in IMX7DRM.pdf wait
> +	 * for PUP_REQ/PDN_REQ bit to be cleared
> +	 */
> +	deadline = jiffies + msecs_to_jiffies(1);
> +	while (true) {
> +		u32 pxx_req;
> +
> +		regmap_read(domain->regmap, offset, &pxx_req);
> +
> +		if (!(pxx_req & domain->bits.pxx))
> +			break;
> +
> +		if (time_after(jiffies, deadline)) {
> +			dev_err(domain->dev, "falied to command PGC\n");
> +			ret = -ETIMEDOUT;
> +			/*
> +			 * If we were in a process of enabling a
> +			 * domain and failed we might as well disable
> +			 * the regulator we just enabled. And if it
> +			 * was the opposite situation and we failed to
> +			 * power down -- keep the regulator on
> +			 */
> +			on = !on;
> +			break;
> +		}
> +
> +		cpu_relax();
> +	}
> +
> +	if (enable_power_control)
> +		regmap_update_bits(domain->regmap, domain->pgc_nctrl,
> +				   GPC_PGC_nCTRL_PCR, 0);
> +
> +	if (has_regulator && !on) {
> +		int err;
> +
> +		err = regulator_disable(domain->regulator);
> +		if (err)
> +			dev_err(domain->dev,
> +				"failed to disable regulator: %d\n", ret);
> +		/* Preserve earlier error code */
> +		ret = ret ?: err;
> +	}
> +unmap:
> +	regmap_update_bits(domain->regmap, GPC_PGC_CPU_MAPPING,
> +			   domain->bits.map, 0);
> +	return ret;
> +}
> +
> +static int imx7_gpc_pu_pgc_sw_pup_req(struct generic_pm_domain *genpd)
> +{
> +	return imx7_gpc_pu_pgc_sw_pxx_req(genpd, true);
> +}
> +
> +static int imx7_gpc_pu_pgc_sw_pdn_req(struct generic_pm_domain *genpd)
> +{
> +	return imx7_gpc_pu_pgc_sw_pxx_req(genpd, false);
> +}
> +
> +static struct imx7_pgc_domain imx7_pgc_domains[] = {
> +	[IMX7_POWER_DOMAIN_USB_HSIC_PHY] = {
> +		.genpd = {
> +			.name      = "usb-hsic-phy",
> +		},
> +		.bits  = {
> +			.pxx = USB_HSIC_PHY_SW_Pxx_REQ,
> +			.map = USB_HSIC_PHY_A7_DOMAIN,
> +		},
> +		.voltage   = 1200000,
> +		.pgc_nctrl = 0x0d00,
> +	},
> +
> +	[IMX7_POWER_DOMAIN_USB_OTG2_PHY] = {
> +		.genpd = {
> +			.name      = "usb-otg2-phy",
> +		},
> +		.bits  = {
> +			.pxx = USB_OTG2_PHY_SW_Pxx_REQ,
> +			.map = USB_OTG2_PHY_A7_DOMAIN,
> +		},
> +	},
> +
> +	[IMX7_POWER_DOMAIN_USB_OTG1_PHY] = {
> +		.genpd = {
> +			.name      = "usb-otg1-phy",
> +		},
> +		.bits  = {
> +			.pxx = USB_OTG1_PHY_SW_Pxx_REQ,
> +			.map = USB_OTG1_PHY_A7_DOMAIN,
> +		},
> +	},
> +
> +	[IMX7_POWER_DOMAIN_PCIE_PHY] = {
> +		.genpd = {
> +			.name      = "pcie-phy",
> +		},
> +		.bits  = {
> +			.pxx = PCIE_PHY_SW_Pxx_REQ,
> +			.map = PCIE_PHY_A7_DOMAIN,
> +		},
> +		.voltage   = 1000000,
> +		.pgc_nctrl = 0x0c40,
> +	},
> +
> +	[IMX7_POWER_DOMAIN_MIPI_PHY] = {
> +		.genpd = {
> +			.name      = "mipi-phy",
> +		},
> +		.bits  = {
> +			.pxx = MIPI_PHY_SW_Pxx_REQ,
> +			.map = MIPI_PHY_A7_DOMAIN,
> +		},
> +		.voltage   = 1000000,
> +		.pgc_nctrl = 0x0c00,
> +	},
> +};
> +
> +static int imx7_pgc_domain_probe(struct platform_device *pdev)
> +{
> +	struct imx7_pgc_domain *domain = pdev->dev.platform_data;
> +	int ret;
> +
> +	domain->dev = &pdev->dev;
> +
> +	ret = pm_genpd_init(&domain->genpd, NULL, true);
> +	if (ret) {
> +		dev_err(domain->dev, "Failed to init power domain\n");
> +		return ret;
> +	}
> +
> +	domain->regulator = devm_regulator_get_optional(domain->dev, "power");
> +	if (IS_ERR(domain->regulator) &&
> +	    PTR_ERR(domain->regulator) != -ENODEV) {
> +		dev_err(domain->dev, "Failed to get domain's regulator\n");
> +		return PTR_ERR(domain->regulator);
> +	}
> +
> +	if (!IS_ERR(domain->regulator)) {
> +		if (!domain->voltage) {
> +			WARN(1, "No voltage configured for domain's regulator");
> +			return -EINVAL;
> +		}
> +
> +		regulator_set_voltage(domain->regulator,
> +				      domain->voltage, domain->voltage);
> +	}
> +
> +	ret = of_genpd_add_provider_simple(domain->dev->of_node,
> +					   &domain->genpd);
> +	if (ret) {
> +		dev_err(domain->dev, "Failed to add genpd provider\n");
> +		pm_genpd_remove(&domain->genpd);
> +	}
> +
> +	return ret;
> +}
> +
> +static int imx7_pgc_domain_remove(struct platform_device *pdev)
> +{
> +	struct imx7_pgc_domain *domain = pdev->dev.platform_data;
> +
> +	of_genpd_del_provider(domain->dev->of_node);
> +	pm_genpd_remove(&domain->genpd);
> +
> +	return 0;
> +}
> +
> +static const struct platform_device_id imx7_pgc_domain_id[] = {
> +	{ "imx7-pgc-domain", },
> +	{ },
> +};
> +
> +static struct platform_driver imx7_pgc_domain_driver = {
> +	.driver = {
> +		.name = "imx7-pgc",
> +	},
> +	.probe    = imx7_pgc_domain_probe,
> +	.remove   = imx7_pgc_domain_remove,
> +	.id_table = imx7_pgc_domain_id,
> +};
> +builtin_platform_driver(imx7_pgc_domain_driver)
> +
> +static bool imx_gpcv2_readable_reg(struct device *dev, unsigned int reg)
> +{
> +	return reg % 4 == 0 &&
> +	       reg <= GPC_MAX_REGISTER;
> +}
> +
> +static bool imx_gpcv2_volatile_reg(struct device *dev, unsigned int reg)
> +{
> +	return reg == GPC_PU_PGC_SW_PUP_REQ ||
> +	       reg == GPC_PU_PGC_SW_PDN_REQ;
> +}
> +
> +static int imx_gpcv2_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *pgc_np, *np;
> +	struct regmap *regmap;
> +	struct resource *res;
> +	void __iomem *base;
> +	int ret;
> +
> +	static const struct regmap_config regmap_config = {
> +		.cache_type	= REGCACHE_FLAT,
> +		.reg_bits	= 32,
> +		.val_bits	= 32,
> +		.reg_stride	= 4,
> +
> +		.readable_reg	= imx_gpcv2_readable_reg,
> +		.volatile_reg	= imx_gpcv2_volatile_reg,
> +
> +		.max_register	= GPC_MAX_REGISTER,
> +	};
> +
> +	pgc_np = of_get_child_by_name(dev->of_node, "pgc");
> +	if (!pgc_np) {
> +		dev_err(dev, "No power domains specified in DT\n");
> +		return -EINVAL;
> +	}
> +
> +	res  = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	regmap = devm_regmap_init_mmio(dev, base, &regmap_config);
> +	if (IS_ERR(regmap)) {
> +		ret = PTR_ERR(regmap);
> +		dev_err(dev, "failed to init regmap (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	for_each_child_of_node(pgc_np, np) {
> +		struct platform_device *pd_pdev;
> +		struct imx7_pgc_domain *domain;
> +		u32 domain_index;
> +
> +		ret = of_property_read_u32(np, "reg", &domain_index);
> +		if (ret) {
> +			dev_err(dev, "Failed to read 'reg' property\n");
> +			of_node_put(np);
> +			return ret;
> +		}
> +
> +		if (domain_index >= ARRAY_SIZE(imx7_pgc_domains)) {
> +			dev_warn(dev,
> +				 "Domain index %d is out of bounds\n",
> +				 domain_index);
> +			continue;
> +		}
> +
> +		domain = &imx7_pgc_domains[domain_index];
> +		domain->regmap = regmap;
> +		domain->genpd.power_on  = imx7_gpc_pu_pgc_sw_pup_req;
> +		domain->genpd.power_off = imx7_gpc_pu_pgc_sw_pdn_req;
> +
> +		pd_pdev = platform_device_alloc("imx7-pgc-domain",
> +						domain_index);
> +		if (!pd_pdev) {
> +			dev_err(dev, "Failed to allocate platform device\n");
> +			of_node_put(np);
> +			return -ENOMEM;
> +		}
> +
> +		pd_pdev->dev.platform_data = domain;
> +		pd_pdev->dev.parent = dev;
> +		pd_pdev->dev.of_node = np;
> +
> +		ret = platform_device_add(pd_pdev);
> +		if (ret) {
> +			platform_device_put(pd_pdev);
> +			of_node_put(np);
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id imx_gpcv2_dt_ids[] = {
> +	{ .compatible = "fsl,imx7d-gpc" },
> +	{ }
> +};
> +
> +static struct platform_driver imx_gpc_driver = {
> +	.driver = {
> +		.name = "imx-gpcv2",
> +		.of_match_table = imx_gpcv2_dt_ids,
> +	},
> +	.probe = imx_gpcv2_probe,
> +};
> +builtin_platform_driver(imx_gpc_driver)
> -- 
> 2.9.3
>
diff mbox

Patch

diff --git a/drivers/soc/Kconfig b/drivers/soc/Kconfig
index f31bceb..55a4eb8 100644
--- a/drivers/soc/Kconfig
+++ b/drivers/soc/Kconfig
@@ -2,6 +2,7 @@  menu "SOC (System On Chip) specific Drivers"
 
 source "drivers/soc/bcm/Kconfig"
 source "drivers/soc/fsl/Kconfig"
+source "drivers/soc/imx/Kconfig"
 source "drivers/soc/mediatek/Kconfig"
 source "drivers/soc/qcom/Kconfig"
 source "drivers/soc/rockchip/Kconfig"
diff --git a/drivers/soc/imx/Kconfig b/drivers/soc/imx/Kconfig
new file mode 100644
index 0000000..9c84eb0
--- /dev/null
+++ b/drivers/soc/imx/Kconfig
@@ -0,0 +1,9 @@ 
+menu "i.MX SoC drivers"
+
+config IMX7_PM_DOMAINS
+	bool "i.MX7 PM domains"
+	select PM_GENERIC_DOMAINS
+	depends on SOC_IMX7D || (COMPILE_TEST && OF)
+
+endmenu
+
diff --git a/drivers/soc/imx/Makefile b/drivers/soc/imx/Makefile
index 35861f5..5b6e396 100644
--- a/drivers/soc/imx/Makefile
+++ b/drivers/soc/imx/Makefile
@@ -1 +1,2 @@ 
 obj-y += gpc.o
+obj-$(CONFIG_IMX7_PM_DOMAINS) += gpcv2.o
diff --git a/drivers/soc/imx/gpcv2.c b/drivers/soc/imx/gpcv2.c
new file mode 100644
index 0000000..7d52141
--- /dev/null
+++ b/drivers/soc/imx/gpcv2.c
@@ -0,0 +1,387 @@ 
+/*
+ * Copyright 2017 Impinj, Inc
+ * Author: Andrey Smirnov <andrew.smirnov@gmail.com>
+ *
+ * Based on the code of analogus driver:
+ *
+ * Copyright 2015-2017 Pengutronix, Lucas Stach <kernel@pengutronix.de>
+ *
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.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>
+#include <dt-bindings/power/imx7-power.h>
+
+#define GPC_PGC_CPU_MAPPING	0xec
+#define USB_HSIC_PHY_A7_DOMAIN	BIT(6)
+#define USB_OTG2_PHY_A7_DOMAIN	BIT(5)
+#define USB_OTG1_PHY_A7_DOMAIN	BIT(4)
+#define PCIE_PHY_A7_DOMAIN	BIT(3)
+#define MIPI_PHY_A7_DOMAIN	BIT(2)
+
+#define GPC_PU_PGC_SW_PUP_REQ	0xf8
+#define GPC_PU_PGC_SW_PDN_REQ	0x104
+#define USB_HSIC_PHY_SW_Pxx_REQ	BIT(4)
+#define USB_OTG2_PHY_SW_Pxx_REQ	BIT(3)
+#define USB_OTG1_PHY_SW_Pxx_REQ	BIT(2)
+#define PCIE_PHY_SW_Pxx_REQ	BIT(1)
+#define MIPI_PHY_SW_Pxx_REQ	BIT(0)
+
+#define GPC_MAX_REGISTER	0x1000
+
+#define GPC_PGC_nCTRL_PCR	BIT(0)
+
+struct imx7_pgc_domain {
+	struct generic_pm_domain genpd;
+	struct regmap *regmap;
+	struct regulator *regulator;
+
+	unsigned int pgc_nctrl;
+
+	const struct {
+		u32 pxx;
+		u32 map;
+	} bits;
+
+	const int voltage;
+	struct device *dev;
+};
+
+static int imx7_gpc_pu_pgc_sw_pxx_req(struct generic_pm_domain *genpd,
+				      bool on)
+{
+	int ret = 0;
+	unsigned long deadline;
+	struct imx7_pgc_domain *domain = container_of(genpd,
+						      struct imx7_pgc_domain,
+						      genpd);
+	unsigned int offset = on ?
+		GPC_PU_PGC_SW_PUP_REQ : GPC_PU_PGC_SW_PDN_REQ;
+
+	const bool enable_power_control = domain->pgc_nctrl && !on;
+	const bool has_regulator = !IS_ERR(domain->regulator);
+
+	regmap_update_bits(domain->regmap, GPC_PGC_CPU_MAPPING,
+			   domain->bits.map, domain->bits.map);
+
+	if (has_regulator && on) {
+		ret = regulator_enable(domain->regulator);
+		if (ret) {
+			dev_err(domain->dev, "failed to enable regulator\n");
+			goto unmap;
+		}
+	}
+
+	if (enable_power_control)
+		regmap_update_bits(domain->regmap, domain->pgc_nctrl,
+				   GPC_PGC_nCTRL_PCR, GPC_PGC_nCTRL_PCR);
+
+	regmap_update_bits(domain->regmap, offset,
+			   domain->bits.pxx, domain->bits.pxx);
+
+	/*
+	 * As per "5.5.9.4 Example Code 4" in IMX7DRM.pdf wait
+	 * for PUP_REQ/PDN_REQ bit to be cleared
+	 */
+	deadline = jiffies + msecs_to_jiffies(1);
+	while (true) {
+		u32 pxx_req;
+
+		regmap_read(domain->regmap, offset, &pxx_req);
+
+		if (!(pxx_req & domain->bits.pxx))
+			break;
+
+		if (time_after(jiffies, deadline)) {
+			dev_err(domain->dev, "falied to command PGC\n");
+			ret = -ETIMEDOUT;
+			/*
+			 * If we were in a process of enabling a
+			 * domain and failed we might as well disable
+			 * the regulator we just enabled. And if it
+			 * was the opposite situation and we failed to
+			 * power down -- keep the regulator on
+			 */
+			on = !on;
+			break;
+		}
+
+		cpu_relax();
+	}
+
+	if (enable_power_control)
+		regmap_update_bits(domain->regmap, domain->pgc_nctrl,
+				   GPC_PGC_nCTRL_PCR, 0);
+
+	if (has_regulator && !on) {
+		int err;
+
+		err = regulator_disable(domain->regulator);
+		if (err)
+			dev_err(domain->dev,
+				"failed to disable regulator: %d\n", ret);
+		/* Preserve earlier error code */
+		ret = ret ?: err;
+	}
+unmap:
+	regmap_update_bits(domain->regmap, GPC_PGC_CPU_MAPPING,
+			   domain->bits.map, 0);
+	return ret;
+}
+
+static int imx7_gpc_pu_pgc_sw_pup_req(struct generic_pm_domain *genpd)
+{
+	return imx7_gpc_pu_pgc_sw_pxx_req(genpd, true);
+}
+
+static int imx7_gpc_pu_pgc_sw_pdn_req(struct generic_pm_domain *genpd)
+{
+	return imx7_gpc_pu_pgc_sw_pxx_req(genpd, false);
+}
+
+static struct imx7_pgc_domain imx7_pgc_domains[] = {
+	[IMX7_POWER_DOMAIN_USB_HSIC_PHY] = {
+		.genpd = {
+			.name      = "usb-hsic-phy",
+		},
+		.bits  = {
+			.pxx = USB_HSIC_PHY_SW_Pxx_REQ,
+			.map = USB_HSIC_PHY_A7_DOMAIN,
+		},
+		.voltage   = 1200000,
+		.pgc_nctrl = 0x0d00,
+	},
+
+	[IMX7_POWER_DOMAIN_USB_OTG2_PHY] = {
+		.genpd = {
+			.name      = "usb-otg2-phy",
+		},
+		.bits  = {
+			.pxx = USB_OTG2_PHY_SW_Pxx_REQ,
+			.map = USB_OTG2_PHY_A7_DOMAIN,
+		},
+	},
+
+	[IMX7_POWER_DOMAIN_USB_OTG1_PHY] = {
+		.genpd = {
+			.name      = "usb-otg1-phy",
+		},
+		.bits  = {
+			.pxx = USB_OTG1_PHY_SW_Pxx_REQ,
+			.map = USB_OTG1_PHY_A7_DOMAIN,
+		},
+	},
+
+	[IMX7_POWER_DOMAIN_PCIE_PHY] = {
+		.genpd = {
+			.name      = "pcie-phy",
+		},
+		.bits  = {
+			.pxx = PCIE_PHY_SW_Pxx_REQ,
+			.map = PCIE_PHY_A7_DOMAIN,
+		},
+		.voltage   = 1000000,
+		.pgc_nctrl = 0x0c40,
+	},
+
+	[IMX7_POWER_DOMAIN_MIPI_PHY] = {
+		.genpd = {
+			.name      = "mipi-phy",
+		},
+		.bits  = {
+			.pxx = MIPI_PHY_SW_Pxx_REQ,
+			.map = MIPI_PHY_A7_DOMAIN,
+		},
+		.voltage   = 1000000,
+		.pgc_nctrl = 0x0c00,
+	},
+};
+
+static int imx7_pgc_domain_probe(struct platform_device *pdev)
+{
+	struct imx7_pgc_domain *domain = pdev->dev.platform_data;
+	int ret;
+
+	domain->dev = &pdev->dev;
+
+	ret = pm_genpd_init(&domain->genpd, NULL, true);
+	if (ret) {
+		dev_err(domain->dev, "Failed to init power domain\n");
+		return ret;
+	}
+
+	domain->regulator = devm_regulator_get_optional(domain->dev, "power");
+	if (IS_ERR(domain->regulator) &&
+	    PTR_ERR(domain->regulator) != -ENODEV) {
+		dev_err(domain->dev, "Failed to get domain's regulator\n");
+		return PTR_ERR(domain->regulator);
+	}
+
+	if (!IS_ERR(domain->regulator)) {
+		if (!domain->voltage) {
+			WARN(1, "No voltage configured for domain's regulator");
+			return -EINVAL;
+		}
+
+		regulator_set_voltage(domain->regulator,
+				      domain->voltage, domain->voltage);
+	}
+
+	ret = of_genpd_add_provider_simple(domain->dev->of_node,
+					   &domain->genpd);
+	if (ret) {
+		dev_err(domain->dev, "Failed to add genpd provider\n");
+		pm_genpd_remove(&domain->genpd);
+	}
+
+	return ret;
+}
+
+static int imx7_pgc_domain_remove(struct platform_device *pdev)
+{
+	struct imx7_pgc_domain *domain = pdev->dev.platform_data;
+
+	of_genpd_del_provider(domain->dev->of_node);
+	pm_genpd_remove(&domain->genpd);
+
+	return 0;
+}
+
+static const struct platform_device_id imx7_pgc_domain_id[] = {
+	{ "imx7-pgc-domain", },
+	{ },
+};
+
+static struct platform_driver imx7_pgc_domain_driver = {
+	.driver = {
+		.name = "imx7-pgc",
+	},
+	.probe    = imx7_pgc_domain_probe,
+	.remove   = imx7_pgc_domain_remove,
+	.id_table = imx7_pgc_domain_id,
+};
+builtin_platform_driver(imx7_pgc_domain_driver)
+
+static bool imx_gpcv2_readable_reg(struct device *dev, unsigned int reg)
+{
+	return reg % 4 == 0 &&
+	       reg <= GPC_MAX_REGISTER;
+}
+
+static bool imx_gpcv2_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return reg == GPC_PU_PGC_SW_PUP_REQ ||
+	       reg == GPC_PU_PGC_SW_PDN_REQ;
+}
+
+static int imx_gpcv2_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *pgc_np, *np;
+	struct regmap *regmap;
+	struct resource *res;
+	void __iomem *base;
+	int ret;
+
+	static const struct regmap_config regmap_config = {
+		.cache_type	= REGCACHE_FLAT,
+		.reg_bits	= 32,
+		.val_bits	= 32,
+		.reg_stride	= 4,
+
+		.readable_reg	= imx_gpcv2_readable_reg,
+		.volatile_reg	= imx_gpcv2_volatile_reg,
+
+		.max_register	= GPC_MAX_REGISTER,
+	};
+
+	pgc_np = of_get_child_by_name(dev->of_node, "pgc");
+	if (!pgc_np) {
+		dev_err(dev, "No power domains specified in DT\n");
+		return -EINVAL;
+	}
+
+	res  = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	regmap = devm_regmap_init_mmio(dev, base, &regmap_config);
+	if (IS_ERR(regmap)) {
+		ret = PTR_ERR(regmap);
+		dev_err(dev, "failed to init regmap (%d)\n", ret);
+		return ret;
+	}
+
+	for_each_child_of_node(pgc_np, np) {
+		struct platform_device *pd_pdev;
+		struct imx7_pgc_domain *domain;
+		u32 domain_index;
+
+		ret = of_property_read_u32(np, "reg", &domain_index);
+		if (ret) {
+			dev_err(dev, "Failed to read 'reg' property\n");
+			of_node_put(np);
+			return ret;
+		}
+
+		if (domain_index >= ARRAY_SIZE(imx7_pgc_domains)) {
+			dev_warn(dev,
+				 "Domain index %d is out of bounds\n",
+				 domain_index);
+			continue;
+		}
+
+		domain = &imx7_pgc_domains[domain_index];
+		domain->regmap = regmap;
+		domain->genpd.power_on  = imx7_gpc_pu_pgc_sw_pup_req;
+		domain->genpd.power_off = imx7_gpc_pu_pgc_sw_pdn_req;
+
+		pd_pdev = platform_device_alloc("imx7-pgc-domain",
+						domain_index);
+		if (!pd_pdev) {
+			dev_err(dev, "Failed to allocate platform device\n");
+			of_node_put(np);
+			return -ENOMEM;
+		}
+
+		pd_pdev->dev.platform_data = domain;
+		pd_pdev->dev.parent = dev;
+		pd_pdev->dev.of_node = np;
+
+		ret = platform_device_add(pd_pdev);
+		if (ret) {
+			platform_device_put(pd_pdev);
+			of_node_put(np);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static const struct of_device_id imx_gpcv2_dt_ids[] = {
+	{ .compatible = "fsl,imx7d-gpc" },
+	{ }
+};
+
+static struct platform_driver imx_gpc_driver = {
+	.driver = {
+		.name = "imx-gpcv2",
+		.of_match_table = imx_gpcv2_dt_ids,
+	},
+	.probe = imx_gpcv2_probe,
+};
+builtin_platform_driver(imx_gpc_driver)