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 <eric@anholt.net>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>

drivers/mfd/bcm2835-pm.c

@@ -3,7 +3,7 @@
  * 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>
@@ -21,11 +21,16 @@ static const struct mfd_cell bcm2835_pm_devs[] = {
 	{ .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)
@@ -39,13 +44,36 @@ static int bcm2835_pm_probe(struct platform_device *pdev)
 	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/

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

@@ -8,6 +8,7 @@
 struct bcm2835_pm {
 	struct device *dev;
 	void __iomem *base;
+	void __iomem *asb;
 };
 
 #endif /* BCM2835_MFD_PM_H */