soc: bcm: bcm2835-pm: Add support for power domains under a new binding.

This provides a free software alternative to raspberrypi-power.c's
firmware calls to manage power domains. It also exposes a reset line,
where previously the vc4 driver had to try to force power off the
domain in order to trigger a reset.

Signed-off-by: Eric Anholt <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Acked-by: Stefan Wahren <[e-mail]>
Signed-off-by: Stefan Wahren <[e-mail]>

drivers/mfd/bcm2835-pm.c

···
  * PM MFD driver for Broadcom BCM2835
  *
  * This driver binds to the PM block and creates the MFD device for
- * the WDT driver.
+ * the WDT and power drivers.
  */
 
 #include <linux/delay.h>
···
 	{ .name = "bcm2835-wdt" },
 };
 
+static const struct mfd_cell bcm2835_power_devs[] = {
+	{ .name = "bcm2835-power" },
+};
+
 static int bcm2835_pm_probe(struct platform_device *pdev)
 {
 	struct resource *res;
 	struct device *dev = &pdev->dev;
 	struct bcm2835_pm *pm;
+	int ret;
 
 	pm = devm_kzalloc(dev, sizeof(*pm), GFP_KERNEL);
 	if (!pm)
···
 	if (IS_ERR(pm->base))
 		return PTR_ERR(pm->base);
 
-	return devm_mfd_add_devices(dev, -1,
-				    bcm2835_pm_devs, ARRAY_SIZE(bcm2835_pm_devs),
-				    NULL, 0, NULL);
+	ret = devm_mfd_add_devices(dev, -1,
+				   bcm2835_pm_devs, ARRAY_SIZE(bcm2835_pm_devs),
+				   NULL, 0, NULL);
+	if (ret)
+		return ret;
+
+	/* We'll use the presence of the AXI ASB regs in the
+	 * bcm2835-pm binding as the key for whether we can reference
+	 * the full PM register range and support power domains.
+	 */
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (res) {
+		pm->asb = devm_ioremap_resource(dev, res);
+		if (IS_ERR(pm->asb))
+			return PTR_ERR(pm->asb);
+
+		ret = devm_mfd_add_devices(dev, -1,
+					   bcm2835_power_devs,
+					   ARRAY_SIZE(bcm2835_power_devs),
+					   NULL, 0, NULL);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
 }
 
 static const struct of_device_id bcm2835_pm_of_match[] = {
 	{ .compatible = "brcm,bcm2835-pm-wdt", },
+	{ .compatible = "brcm,bcm2835-pm", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, bcm2835_pm_of_match);

drivers/soc/bcm/Kconfig

···
 menu "Broadcom SoC drivers"
 
+config BCM2835_POWER
+	bool "BCM2835 power domain driver"
+	depends on ARCH_BCM2835 || (COMPILE_TEST && OF)
+	select PM_GENERIC_DOMAINS if PM
+	select RESET_CONTROLLER
+	help
+	  This enables support for the BCM2835 power domains and reset
+	  controller.  Any usage of power domains by the Raspberry Pi
+	  firmware means that Linux usage of the same power domain
+	  must be accessed using the RASPBERRYPI_POWER driver
+
 config RASPBERRYPI_POWER
 	bool "Raspberry Pi power domain driver"
 	depends on ARCH_BCM2835 || (COMPILE_TEST && OF)

drivers/soc/bcm/Makefile

···
+obj-$(CONFIG_BCM2835_POWER)	+= bcm2835-power.o
 obj-$(CONFIG_RASPBERRYPI_POWER)	+= raspberrypi-power.o
 obj-$(CONFIG_SOC_BRCMSTB)	+= brcmstb/

drivers/soc/bcm/bcm2835-power.c

···
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Power domain driver for Broadcom BCM2835
+ *
+ * Copyright (C) 2018 Broadcom
+ */
+
+#include <dt-bindings/soc/bcm2835-pm.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/mfd/bcm2835-pm.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <linux/reset-controller.h>
+#include <linux/types.h>
+
+#define PM_GNRIC                        0x00
+#define PM_AUDIO                        0x04
+#define PM_STATUS                       0x18
+#define PM_RSTC				0x1c
+#define PM_RSTS				0x20
+#define PM_WDOG				0x24
+#define PM_PADS0			0x28
+#define PM_PADS2			0x2c
+#define PM_PADS3			0x30
+#define PM_PADS4			0x34
+#define PM_PADS5			0x38
+#define PM_PADS6			0x3c
+#define PM_CAM0				0x44
+#define PM_CAM0_LDOHPEN			BIT(2)
+#define PM_CAM0_LDOLPEN			BIT(1)
+#define PM_CAM0_CTRLEN			BIT(0)
+
+#define PM_CAM1				0x48
+#define PM_CAM1_LDOHPEN			BIT(2)
+#define PM_CAM1_LDOLPEN			BIT(1)
+#define PM_CAM1_CTRLEN			BIT(0)
+
+#define PM_CCP2TX			0x4c
+#define PM_CCP2TX_LDOEN			BIT(1)
+#define PM_CCP2TX_CTRLEN		BIT(0)
+
+#define PM_DSI0				0x50
+#define PM_DSI0_LDOHPEN			BIT(2)
+#define PM_DSI0_LDOLPEN			BIT(1)
+#define PM_DSI0_CTRLEN			BIT(0)
+
+#define PM_DSI1				0x54
+#define PM_DSI1_LDOHPEN			BIT(2)
+#define PM_DSI1_LDOLPEN			BIT(1)
+#define PM_DSI1_CTRLEN			BIT(0)
+
+#define PM_HDMI				0x58
+#define PM_HDMI_RSTDR			BIT(19)
+#define PM_HDMI_LDOPD			BIT(1)
+#define PM_HDMI_CTRLEN			BIT(0)
+
+#define PM_USB				0x5c
+/* The power gates must be enabled with this bit before enabling the LDO in the
+ * USB block.
+ */
+#define PM_USB_CTRLEN			BIT(0)
+
+#define PM_PXLDO			0x60
+#define PM_PXBG				0x64
+#define PM_DFT				0x68
+#define PM_SMPS				0x6c
+#define PM_XOSC				0x70
+#define PM_SPAREW			0x74
+#define PM_SPARER			0x78
+#define PM_AVS_RSTDR			0x7c
+#define PM_AVS_STAT			0x80
+#define PM_AVS_EVENT			0x84
+#define PM_AVS_INTEN			0x88
+#define PM_DUMMY			0xfc
+
+#define PM_IMAGE			0x108
+#define PM_GRAFX			0x10c
+#define PM_PROC				0x110
+#define PM_ENAB				BIT(12)
+#define PM_ISPRSTN			BIT(8)
+#define PM_H264RSTN			BIT(7)
+#define PM_PERIRSTN			BIT(6)
+#define PM_V3DRSTN			BIT(6)
+#define PM_ISFUNC			BIT(5)
+#define PM_MRDONE			BIT(4)
+#define PM_MEMREP			BIT(3)
+#define PM_ISPOW			BIT(2)
+#define PM_POWOK			BIT(1)
+#define PM_POWUP			BIT(0)
+#define PM_INRUSH_SHIFT			13
+#define PM_INRUSH_3_5_MA		0
+#define PM_INRUSH_5_MA			1
+#define PM_INRUSH_10_MA			2
+#define PM_INRUSH_20_MA			3
+#define PM_INRUSH_MASK			(3 << PM_INRUSH_SHIFT)
+
+#define PM_PASSWORD			0x5a000000
+
+#define PM_WDOG_TIME_SET		0x000fffff
+#define PM_RSTC_WRCFG_CLR		0xffffffcf
+#define PM_RSTS_HADWRH_SET		0x00000040
+#define PM_RSTC_WRCFG_SET		0x00000030
+#define PM_RSTC_WRCFG_FULL_RESET	0x00000020
+#define PM_RSTC_RESET			0x00000102
+
+#define PM_READ(reg) readl(power->base + (reg))
+#define PM_WRITE(reg, val) writel(PM_PASSWORD | (val), power->base + (reg))
+
+#define ASB_BRDG_VERSION                0x00
+#define ASB_CPR_CTRL                    0x04
+
+#define ASB_V3D_S_CTRL			0x08
+#define ASB_V3D_M_CTRL			0x0c
+#define ASB_ISP_S_CTRL			0x10
+#define ASB_ISP_M_CTRL			0x14
+#define ASB_H264_S_CTRL			0x18
+#define ASB_H264_M_CTRL			0x1c
+
+#define ASB_REQ_STOP                    BIT(0)
+#define ASB_ACK                         BIT(1)
+#define ASB_EMPTY                       BIT(2)
+#define ASB_FULL                        BIT(3)
+
+#define ASB_AXI_BRDG_ID			0x20
+
+#define ASB_READ(reg) readl(power->asb + (reg))
+#define ASB_WRITE(reg, val) writel(PM_PASSWORD | (val), power->asb + (reg))
+
+struct bcm2835_power_domain {
+	struct generic_pm_domain base;
+	struct bcm2835_power *power;
+	u32 domain;
+	struct clk *clk;
+};
+
+struct bcm2835_power {
+	struct device		*dev;
+	/* PM registers. */
+	void __iomem		*base;
+	/* AXI Async bridge registers. */
+	void __iomem		*asb;
+
+	struct genpd_onecell_data pd_xlate;
+	struct bcm2835_power_domain domains[BCM2835_POWER_DOMAIN_COUNT];
+	struct reset_controller_dev reset;
+};
+
+static int bcm2835_asb_enable(struct bcm2835_power *power, u32 reg)
+{
+	u64 start = ktime_get_ns();
+
+	/* Enable the module's async AXI bridges. */
+	ASB_WRITE(reg, ASB_READ(reg) & ~ASB_REQ_STOP);
+	while (ASB_READ(reg) & ASB_ACK) {
+		cpu_relax();
+		if (ktime_get_ns() - start >= 1000)
+			return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static int bcm2835_asb_disable(struct bcm2835_power *power, u32 reg)
+{
+	u64 start = ktime_get_ns();
+
+	/* Enable the module's async AXI bridges. */
+	ASB_WRITE(reg, ASB_READ(reg) | ASB_REQ_STOP);
+	while (!(ASB_READ(reg) & ASB_ACK)) {
+		cpu_relax();
+		if (ktime_get_ns() - start >= 1000)
+			return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static int bcm2835_power_power_off(struct bcm2835_power_domain *pd, u32 pm_reg)
+{
+	struct bcm2835_power *power = pd->power;
+
+	/* Enable functional isolation */
+	PM_WRITE(pm_reg, PM_READ(pm_reg) & ~PM_ISFUNC);
+
+	/* Enable electrical isolation */
+	PM_WRITE(pm_reg, PM_READ(pm_reg) & ~PM_ISPOW);
+
+	/* Open the power switches. */
+	PM_WRITE(pm_reg, PM_READ(pm_reg) & ~PM_POWUP);
+
+	return 0;
+}
+
+static int bcm2835_power_power_on(struct bcm2835_power_domain *pd, u32 pm_reg)
+{
+	struct bcm2835_power *power = pd->power;
+	struct device *dev = power->dev;
+	u64 start;
+	int ret;
+	int inrush;
+	bool powok;
+
+	/* If it was already powered on by the fw, leave it that way. */
+	if (PM_READ(pm_reg) & PM_POWUP)
+		return 0;
+
+	/* Enable power.  Allowing too much current at once may result
+	 * in POWOK never getting set, so start low and ramp it up as
+	 * necessary to succeed.
+	 */
+	powok = false;
+	for (inrush = PM_INRUSH_3_5_MA; inrush <= PM_INRUSH_20_MA; inrush++) {
+		PM_WRITE(pm_reg,
+			 (PM_READ(pm_reg) & ~PM_INRUSH_MASK) |
+			 (inrush << PM_INRUSH_SHIFT) |
+			 PM_POWUP);
+
+		start = ktime_get_ns();
+		while (!(powok = !!(PM_READ(pm_reg) & PM_POWOK))) {
+			cpu_relax();
+			if (ktime_get_ns() - start >= 3000)
+				break;
+		}
+	}
+	if (!powok) {
+		dev_err(dev, "Timeout waiting for %s power OK\n",
+			pd->base.name);
+		ret = -ETIMEDOUT;
+		goto err_disable_powup;
+	}
+
+	/* Disable electrical isolation */
+	PM_WRITE(pm_reg, PM_READ(pm_reg) | PM_ISPOW);
+
+	/* Repair memory */
+	PM_WRITE(pm_reg, PM_READ(pm_reg) | PM_MEMREP);
+	start = ktime_get_ns();
+	while (!(PM_READ(pm_reg) & PM_MRDONE)) {
+		cpu_relax();
+		if (ktime_get_ns() - start >= 1000) {
+			dev_err(dev, "Timeout waiting for %s memory repair\n",
+				pd->base.name);
+			ret = -ETIMEDOUT;
+			goto err_disable_ispow;
+		}
+	}
+
+	/* Disable functional isolation */
+	PM_WRITE(pm_reg, PM_READ(pm_reg) | PM_ISFUNC);
+
+	return 0;
+
+err_disable_ispow:
+	PM_WRITE(pm_reg, PM_READ(pm_reg) & ~PM_ISPOW);
+err_disable_powup:
+	PM_WRITE(pm_reg, PM_READ(pm_reg) & ~(PM_POWUP | PM_INRUSH_MASK));
+	return ret;
+}
+
+static int bcm2835_asb_power_on(struct bcm2835_power_domain *pd,
+				u32 pm_reg,
+				u32 asb_m_reg,
+				u32 asb_s_reg,
+				u32 reset_flags)
+{
+	struct bcm2835_power *power = pd->power;
+	int ret;
+
+	ret = clk_prepare_enable(pd->clk);
+	if (ret) {
+		dev_err(power->dev, "Failed to enable clock for %s\n",
+			pd->base.name);
+		return ret;
+	}
+
+	/* Wait 32 clocks for reset to propagate, 1 us will be enough */
+	udelay(1);
+
+	clk_disable_unprepare(pd->clk);
+
+	/* Deassert the resets. */
+	PM_WRITE(pm_reg, PM_READ(pm_reg) | reset_flags);
+
+	ret = clk_prepare_enable(pd->clk);
+	if (ret) {
+		dev_err(power->dev, "Failed to enable clock for %s\n",
+			pd->base.name);
+		goto err_enable_resets;
+	}
+
+	ret = bcm2835_asb_enable(power, asb_m_reg);
+	if (ret) {
+		dev_err(power->dev, "Failed to enable ASB master for %s\n",
+			pd->base.name);
+		goto err_disable_clk;
+	}
+	ret = bcm2835_asb_enable(power, asb_s_reg);
+	if (ret) {
+		dev_err(power->dev, "Failed to enable ASB slave for %s\n",
+			pd->base.name);
+		goto err_disable_asb_master;
+	}
+
+	return 0;
+
+err_disable_asb_master:
+	bcm2835_asb_disable(power, asb_m_reg);
+err_disable_clk:
+	clk_disable_unprepare(pd->clk);
+err_enable_resets:
+	PM_WRITE(pm_reg, PM_READ(pm_reg) & ~reset_flags);
+	return ret;
+}
+
+static int bcm2835_asb_power_off(struct bcm2835_power_domain *pd,
+				 u32 pm_reg,
+				 u32 asb_m_reg,
+				 u32 asb_s_reg,
+				 u32 reset_flags)
+{
+	struct bcm2835_power *power = pd->power;
+	int ret;
+
+	ret = bcm2835_asb_disable(power, asb_s_reg);
+	if (ret) {
+		dev_warn(power->dev, "Failed to disable ASB slave for %s\n",
+			 pd->base.name);
+		return ret;
+	}
+	ret = bcm2835_asb_disable(power, asb_m_reg);
+	if (ret) {
+		dev_warn(power->dev, "Failed to disable ASB master for %s\n",
+			 pd->base.name);
+		bcm2835_asb_enable(power, asb_s_reg);
+		return ret;
+	}
+
+	clk_disable_unprepare(pd->clk);
+
+	/* Assert the resets. */
+	PM_WRITE(pm_reg, PM_READ(pm_reg) & ~reset_flags);
+
+	return 0;
+}
+
+static int bcm2835_power_pd_power_on(struct generic_pm_domain *domain)
+{
+	struct bcm2835_power_domain *pd =
+		container_of(domain, struct bcm2835_power_domain, base);
+	struct bcm2835_power *power = pd->power;
+
+	switch (pd->domain) {
+	case BCM2835_POWER_DOMAIN_GRAFX:
+		return bcm2835_power_power_on(pd, PM_GRAFX);
+
+	case BCM2835_POWER_DOMAIN_GRAFX_V3D:
+		return bcm2835_asb_power_on(pd, PM_GRAFX,
+					    ASB_V3D_M_CTRL, ASB_V3D_S_CTRL,
+					    PM_V3DRSTN);
+
+	case BCM2835_POWER_DOMAIN_IMAGE:
+		return bcm2835_power_power_on(pd, PM_IMAGE);
+
+	case BCM2835_POWER_DOMAIN_IMAGE_PERI:
+		return bcm2835_asb_power_on(pd, PM_IMAGE,
+					    0, 0,
+					    PM_PERIRSTN);
+
+	case BCM2835_POWER_DOMAIN_IMAGE_ISP:
+		return bcm2835_asb_power_on(pd, PM_IMAGE,
+					    ASB_ISP_M_CTRL, ASB_ISP_S_CTRL,
+					    PM_ISPRSTN);
+
+	case BCM2835_POWER_DOMAIN_IMAGE_H264:
+		return bcm2835_asb_power_on(pd, PM_IMAGE,
+					    ASB_H264_M_CTRL, ASB_H264_S_CTRL,
+					    PM_H264RSTN);
+
+	case BCM2835_POWER_DOMAIN_USB:
+		PM_WRITE(PM_USB, PM_USB_CTRLEN);
+		return 0;
+
+	case BCM2835_POWER_DOMAIN_DSI0:
+		PM_WRITE(PM_DSI0, PM_DSI0_CTRLEN);
+		PM_WRITE(PM_DSI0, PM_DSI0_CTRLEN | PM_DSI0_LDOHPEN);
+		return 0;
+
+	case BCM2835_POWER_DOMAIN_DSI1:
+		PM_WRITE(PM_DSI1, PM_DSI1_CTRLEN);
+		PM_WRITE(PM_DSI1, PM_DSI1_CTRLEN | PM_DSI1_LDOHPEN);
+		return 0;
+
+	case BCM2835_POWER_DOMAIN_CCP2TX:
+		PM_WRITE(PM_CCP2TX, PM_CCP2TX_CTRLEN);
+		PM_WRITE(PM_CCP2TX, PM_CCP2TX_CTRLEN | PM_CCP2TX_LDOEN);
+		return 0;
+
+	case BCM2835_POWER_DOMAIN_HDMI:
+		PM_WRITE(PM_HDMI, PM_READ(PM_HDMI) | PM_HDMI_RSTDR);
+		PM_WRITE(PM_HDMI, PM_READ(PM_HDMI) | PM_HDMI_CTRLEN);
+		PM_WRITE(PM_HDMI, PM_READ(PM_HDMI) & ~PM_HDMI_LDOPD);
+		usleep_range(100, 200);
+		PM_WRITE(PM_HDMI, PM_READ(PM_HDMI) & ~PM_HDMI_RSTDR);
+		return 0;
+
+	default:
+		dev_err(power->dev, "Invalid domain %d\n", pd->domain);
+		return -EINVAL;
+	}
+}
+
+static int bcm2835_power_pd_power_off(struct generic_pm_domain *domain)
+{
+	struct bcm2835_power_domain *pd =
+		container_of(domain, struct bcm2835_power_domain, base);
+	struct bcm2835_power *power = pd->power;
+
+	switch (pd->domain) {
+	case BCM2835_POWER_DOMAIN_GRAFX:
+		return bcm2835_power_power_off(pd, PM_GRAFX);
+
+	case BCM2835_POWER_DOMAIN_GRAFX_V3D:
+		return bcm2835_asb_power_off(pd, PM_GRAFX,
+					     ASB_V3D_M_CTRL, ASB_V3D_S_CTRL,
+					     PM_V3DRSTN);
+
+	case BCM2835_POWER_DOMAIN_IMAGE:
+		return bcm2835_power_power_off(pd, PM_IMAGE);
+
+	case BCM2835_POWER_DOMAIN_IMAGE_PERI:
+		return bcm2835_asb_power_off(pd, PM_IMAGE,
+					     0, 0,
+					     PM_PERIRSTN);
+
+	case BCM2835_POWER_DOMAIN_IMAGE_ISP:
+		return bcm2835_asb_power_off(pd, PM_IMAGE,
+					     ASB_ISP_M_CTRL, ASB_ISP_S_CTRL,
+					     PM_ISPRSTN);
+
+	case BCM2835_POWER_DOMAIN_IMAGE_H264:
+		return bcm2835_asb_power_off(pd, PM_IMAGE,
+					     ASB_H264_M_CTRL, ASB_H264_S_CTRL,
+					     PM_H264RSTN);
+
+	case BCM2835_POWER_DOMAIN_USB:
+		PM_WRITE(PM_USB, 0);
+		return 0;
+
+	case BCM2835_POWER_DOMAIN_DSI0:
+		PM_WRITE(PM_DSI0, PM_DSI0_CTRLEN);
+		PM_WRITE(PM_DSI0, 0);
+		return 0;
+
+	case BCM2835_POWER_DOMAIN_DSI1:
+		PM_WRITE(PM_DSI1, PM_DSI1_CTRLEN);
+		PM_WRITE(PM_DSI1, 0);
+		return 0;
+
+	case BCM2835_POWER_DOMAIN_CCP2TX:
+		PM_WRITE(PM_CCP2TX, PM_CCP2TX_CTRLEN);
+		PM_WRITE(PM_CCP2TX, 0);
+		return 0;
+
+	case BCM2835_POWER_DOMAIN_HDMI:
+		PM_WRITE(PM_HDMI, PM_READ(PM_HDMI) | PM_HDMI_LDOPD);
+		PM_WRITE(PM_HDMI, PM_READ(PM_HDMI) & ~PM_HDMI_CTRLEN);
+		return 0;
+
+	default:
+		dev_err(power->dev, "Invalid domain %d\n", pd->domain);
+		return -EINVAL;
+	}
+}
+
+static void
+bcm2835_init_power_domain(struct bcm2835_power *power,
+			  int pd_xlate_index, const char *name)
+{
+	struct device *dev = power->dev;
+	struct bcm2835_power_domain *dom = &power->domains[pd_xlate_index];
+
+	dom->clk = devm_clk_get(dev->parent, name);
+
+	dom->base.name = name;
+	dom->base.power_on = bcm2835_power_pd_power_on;
+	dom->base.power_off = bcm2835_power_pd_power_off;
+
+	dom->domain = pd_xlate_index;
+	dom->power = power;
+
+	/* XXX: on/off at boot? */
+	pm_genpd_init(&dom->base, NULL, true);
+
+	power->pd_xlate.domains[pd_xlate_index] = &dom->base;
+}
+
+/** bcm2835_reset_reset - Resets a block that has a reset line in the
+ * PM block.
+ *
+ * The consumer of the reset controller must have the power domain up
+ * -- there's no reset ability with the power domain down.  To reset
+ * the sub-block, we just disable its access to memory through the
+ * ASB, reset, and re-enable.
+ */
+static int bcm2835_reset_reset(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	struct bcm2835_power *power = container_of(rcdev, struct bcm2835_power,
+						   reset);
+	struct bcm2835_power_domain *pd;
+	int ret;
+
+	switch (id) {
+	case BCM2835_RESET_V3D:
+		pd = &power->domains[BCM2835_POWER_DOMAIN_GRAFX_V3D];
+		break;
+	case BCM2835_RESET_H264:
+		pd = &power->domains[BCM2835_POWER_DOMAIN_IMAGE_H264];
+		break;
+	case BCM2835_RESET_ISP:
+		pd = &power->domains[BCM2835_POWER_DOMAIN_IMAGE_ISP];
+		break;
+	default:
+		dev_err(power->dev, "Bad reset id %ld\n", id);
+		return -EINVAL;
+	}
+
+	ret = bcm2835_power_pd_power_off(&pd->base);
+	if (ret)
+		return ret;
+
+	return bcm2835_power_pd_power_on(&pd->base);
+}
+
+static int bcm2835_reset_status(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct bcm2835_power *power = container_of(rcdev, struct bcm2835_power,
+						   reset);
+
+	switch (id) {
+	case BCM2835_RESET_V3D:
+		return !PM_READ(PM_GRAFX & PM_V3DRSTN);
+	case BCM2835_RESET_H264:
+		return !PM_READ(PM_IMAGE & PM_H264RSTN);
+	case BCM2835_RESET_ISP:
+		return !PM_READ(PM_IMAGE & PM_ISPRSTN);
+	default:
+		return -EINVAL;
+	}
+}
+
+const struct reset_control_ops bcm2835_reset_ops = {
+	.reset = bcm2835_reset_reset,
+	.status = bcm2835_reset_status,
+};
+
+static const char *const power_domain_names[] = {
+	[BCM2835_POWER_DOMAIN_GRAFX] = "grafx",
+	[BCM2835_POWER_DOMAIN_GRAFX_V3D] = "v3d",
+
+	[BCM2835_POWER_DOMAIN_IMAGE] = "image",
+	[BCM2835_POWER_DOMAIN_IMAGE_PERI] = "peri_image",
+	[BCM2835_POWER_DOMAIN_IMAGE_H264] = "h264",
+	[BCM2835_POWER_DOMAIN_IMAGE_ISP] = "isp",
+
+	[BCM2835_POWER_DOMAIN_USB] = "usb",
+	[BCM2835_POWER_DOMAIN_DSI0] = "dsi0",
+	[BCM2835_POWER_DOMAIN_DSI1] = "dsi1",
+	[BCM2835_POWER_DOMAIN_CAM0] = "cam0",
+	[BCM2835_POWER_DOMAIN_CAM1] = "cam1",
+	[BCM2835_POWER_DOMAIN_CCP2TX] = "ccp2tx",
+	[BCM2835_POWER_DOMAIN_HDMI] = "hdmi",
+};
+
+static int bcm2835_power_probe(struct platform_device *pdev)
+{
+	struct bcm2835_pm *pm = dev_get_drvdata(pdev->dev.parent);
+	struct device *dev = &pdev->dev;
+	struct bcm2835_power *power;
+	static const struct {
+		int parent, child;
+	} domain_deps[] = {
+		{ BCM2835_POWER_DOMAIN_GRAFX, BCM2835_POWER_DOMAIN_GRAFX_V3D },
+		{ BCM2835_POWER_DOMAIN_IMAGE, BCM2835_POWER_DOMAIN_IMAGE_PERI },
+		{ BCM2835_POWER_DOMAIN_IMAGE, BCM2835_POWER_DOMAIN_IMAGE_H264 },
+		{ BCM2835_POWER_DOMAIN_IMAGE, BCM2835_POWER_DOMAIN_IMAGE_ISP },
+		{ BCM2835_POWER_DOMAIN_IMAGE_PERI, BCM2835_POWER_DOMAIN_USB },
+		{ BCM2835_POWER_DOMAIN_IMAGE_PERI, BCM2835_POWER_DOMAIN_CAM0 },
+		{ BCM2835_POWER_DOMAIN_IMAGE_PERI, BCM2835_POWER_DOMAIN_CAM1 },
+	};
+	int ret, i;
+	u32 id;
+
+	power = devm_kzalloc(dev, sizeof(*power), GFP_KERNEL);
+	if (!power)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, power);
+
+	power->dev = dev;
+	power->base = pm->base;
+	power->asb = pm->asb;
+
+	id = ASB_READ(ASB_AXI_BRDG_ID);
+	if (id != 0x62726467 /* "BRDG" */) {
+		dev_err(dev, "ASB register ID returned 0x%08x\n", id);
+		return -ENODEV;
+	}
+
+	power->pd_xlate.domains = devm_kcalloc(dev,
+					       ARRAY_SIZE(power_domain_names),
+					       sizeof(*power->pd_xlate.domains),
+					       GFP_KERNEL);
+	if (!power->pd_xlate.domains)
+		return -ENOMEM;
+
+	power->pd_xlate.num_domains = ARRAY_SIZE(power_domain_names);
+
+	for (i = 0; i < ARRAY_SIZE(power_domain_names); i++)
+		bcm2835_init_power_domain(power, i, power_domain_names[i]);
+
+	for (i = 0; i < ARRAY_SIZE(domain_deps); i++) {
+		pm_genpd_add_subdomain(&power->domains[domain_deps[i].parent].base,
+				       &power->domains[domain_deps[i].child].base);
+	}
+
+	power->reset.owner = THIS_MODULE;
+	power->reset.nr_resets = BCM2835_RESET_COUNT;
+	power->reset.ops = &bcm2835_reset_ops;
+	power->reset.of_node = dev->parent->of_node;
+
+	ret = devm_reset_controller_register(dev, &power->reset);
+	if (ret)
+		return ret;
+
+	of_genpd_add_provider_onecell(dev->parent->of_node, &power->pd_xlate);
+
+	dev_info(dev, "Broadcom BCM2835 power domains driver");
+	return 0;
+}
+
+static int bcm2835_power_remove(struct platform_device *pdev)
+{
+	return 0;
+}
+
+static struct platform_driver bcm2835_power_driver = {
+	.probe		= bcm2835_power_probe,
+	.remove		= bcm2835_power_remove,
+	.driver = {
+		.name =	"bcm2835-power",
+	},
+};
+module_platform_driver(bcm2835_power_driver);
+
+MODULE_AUTHOR("Eric Anholt <[e-mail]>");
+MODULE_DESCRIPTION("Driver for Broadcom BCM2835 PM power domains and reset");
+MODULE_LICENSE("GPL");

include/dt-bindings/soc/bcm2835-pm.h

···
+/* SPDX-License-Identifier: (GPL-2.0+ OR MIT) */
+
+#ifndef _DT_BINDINGS_ARM_BCM2835_PM_H
+#define _DT_BINDINGS_ARM_BCM2835_PM_H
+
+#define BCM2835_POWER_DOMAIN_GRAFX		0
+#define BCM2835_POWER_DOMAIN_GRAFX_V3D		1
+#define BCM2835_POWER_DOMAIN_IMAGE		2
+#define BCM2835_POWER_DOMAIN_IMAGE_PERI		3
+#define BCM2835_POWER_DOMAIN_IMAGE_ISP		4
+#define BCM2835_POWER_DOMAIN_IMAGE_H264		5
+#define BCM2835_POWER_DOMAIN_USB		6
+#define BCM2835_POWER_DOMAIN_DSI0		7
+#define BCM2835_POWER_DOMAIN_DSI1		8
+#define BCM2835_POWER_DOMAIN_CAM0		9
+#define BCM2835_POWER_DOMAIN_CAM1		10
+#define BCM2835_POWER_DOMAIN_CCP2TX		11
+#define BCM2835_POWER_DOMAIN_HDMI		12
+
+#define BCM2835_POWER_DOMAIN_COUNT		13
+
+#define BCM2835_RESET_V3D			0
+#define BCM2835_RESET_ISP			1
+#define BCM2835_RESET_H264			2
+
+#define BCM2835_RESET_COUNT			3
+
+#endif /* _DT_BINDINGS_ARM_BCM2835_PM_H */

include/linux/mfd/bcm2835-pm.h

···
 struct bcm2835_pm {
 	struct device *dev;
 	void __iomem *base;
+	void __iomem *asb;
 };
 
 #endif /* BCM2835_MFD_PM_H */