button: qcom-pmic: introduce Qualcomm PMIC button driver

Qualcomm PMICs include a "pon" function which handles two buttons, the
power button and "resin" button (usually volume down). Introduce a new
driver following upstream Linux DT to enable these and map them to Enter
and Down respectively to enable use in boot menus.

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Tested-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>

MAINTAINERS

@@ -575,6 +575,7 @@ M:	Neil Armstrong <neil.armstrong@linaro.org>
 R:	Sumit Garg <sumit.garg@linaro.org>
 S:	Maintained
 F:	arch/arm/mach-snapdragon/
+F:	drivers/button/button-qcom-pmic.c
 F:	drivers/clk/qcom/
 F:	drivers/gpio/msm_gpio.c
 F:	drivers/mmc/msm_sdhci.c

drivers/button/Kconfig

@@ -27,4 +27,13 @@ config BUTTON_GPIO
 	  The GPIO driver must used driver model. Buttons are configured using
 	  the device tree.
 
+config BUTTON_QCOM_PMIC
+	bool "Qualcomm power button"
+	depends on BUTTON
+	depends on PMIC_QCOM
+	help
+	  Enable support for the power and "resin" (usually volume down) buttons
+	  on Qualcomm SoCs. These will be configured as the Enter and Down keys
+	  respectively, allowing navigation of bootmenu with buttons on device.
+
 endmenu

drivers/button/Makefile

@@ -5,3 +5,4 @@
 obj-$(CONFIG_BUTTON) += button-uclass.o
 obj-$(CONFIG_BUTTON_ADC) += button-adc.o
 obj-$(CONFIG_BUTTON_GPIO) += button-gpio.o
+obj-$(CONFIG_BUTTON_QCOM_PMIC) += button-qcom-pmic.o

drivers/button/button-qcom-pmic.c

@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Qualcomm generic pmic gpio driver
+ *
+ * (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
+ * (C) Copyright 2023 Linaro Ltd.
+ */
+
+#include <button.h>
+#include <dt-bindings/input/linux-event-codes.h>
+#include <dm.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+#include <log.h>
+#include <power/pmic.h>
+#include <spmi/spmi.h>
+#include <linux/bitops.h>
+
+#define REG_TYPE		0x4
+#define REG_SUBTYPE		0x5
+
+struct qcom_pmic_btn_priv {
+	u32 base;
+	u32 status_bit;
+	int code;
+	struct udevice *pmic;
+};
+
+#define PON_INT_RT_STS                        0x10
+#define KPDPWR_ON_INT_BIT                     0
+#define RESIN_ON_INT_BIT                      1
+
+#define NODE_IS_PWRKEY(node) (!strncmp(ofnode_get_name(node), "pwrkey", strlen("pwrkey")))
+#define NODE_IS_RESIN(node) (!strncmp(ofnode_get_name(node), "resin", strlen("resin")))
+
+static enum button_state_t qcom_pwrkey_get_state(struct udevice *dev)
+{
+	struct qcom_pmic_btn_priv *priv = dev_get_priv(dev);
+
+	int reg = pmic_reg_read(priv->pmic, priv->base + PON_INT_RT_STS);
+
+	if (reg < 0)
+		return 0;
+
+	return (reg & BIT(priv->status_bit)) != 0;
+}
+
+static int qcom_pwrkey_get_code(struct udevice *dev)
+{
+	struct qcom_pmic_btn_priv *priv = dev_get_priv(dev);
+
+	return priv->code;
+}
+
+static int qcom_pwrkey_probe(struct udevice *dev)
+{
+	struct button_uc_plat *uc_plat = dev_get_uclass_plat(dev);
+	struct qcom_pmic_btn_priv *priv = dev_get_priv(dev);
+	ofnode node = dev_ofnode(dev);
+	int ret;
+	u64 base;
+
+	/* Ignore the top-level pon node */
+	if (!uc_plat->label)
+		return 0;
+
+	/* the pwrkey and resin nodes are children of the "pon" node, get the
+	 * PMIC device to use in pmic_reg_* calls.
+	 */
+	priv->pmic = dev->parent->parent;
+
+	/* Get the address of the parent pon node */
+	base = dev_read_addr(dev->parent);
+	if (base == FDT_ADDR_T_NONE) {
+		printf("%s: Can't find address\n", dev->name);
+		return -EINVAL;
+	}
+
+	priv->base = base;
+
+	/* Do a sanity check */
+	ret = pmic_reg_read(priv->pmic, priv->base + REG_TYPE);
+	if (ret != 0x1 && ret != 0xb) {
+		printf("%s: unexpected PMIC function type %d\n", dev->name, ret);
+		return -ENXIO;
+	}
+
+	ret = pmic_reg_read(priv->pmic, priv->base + REG_SUBTYPE);
+	if ((ret & 0x7) == 0) {
+		printf("%s: unexpected PMCI function subtype %d\n", dev->name, ret);
+		return -ENXIO;
+	}
+
+	if (NODE_IS_PWRKEY(node)) {
+		priv->status_bit = 0;
+		priv->code = KEY_ENTER;
+	} else if (NODE_IS_RESIN(node)) {
+		priv->status_bit = 1;
+		priv->code = KEY_DOWN;
+	} else {
+		/* Should not get here! */
+		printf("Invalid pon node '%s' should be 'pwrkey' or 'resin'\n",
+		       ofnode_get_name(node));
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int button_qcom_pmic_bind(struct udevice *parent)
+{
+	struct udevice *dev;
+	ofnode node;
+	int ret;
+
+	dev_for_each_subnode(node, parent) {
+		struct button_uc_plat *uc_plat;
+		const char *label;
+
+		if (!ofnode_is_enabled(node))
+			continue;
+
+		ret = device_bind_driver_to_node(parent, "qcom_pwrkey",
+						 ofnode_get_name(node),
+						 node, &dev);
+		if (ret) {
+			printf("Failed to bind %s! %d\n", label, ret);
+			return ret;
+		}
+		uc_plat = dev_get_uclass_plat(dev);
+		if (NODE_IS_PWRKEY(node)) {
+			uc_plat->label = "pwrkey";
+		} else if (NODE_IS_RESIN(node)) {
+			uc_plat->label = "vol_down";
+		} else {
+			printf("Unknown button node '%s' should be 'pwrkey' or 'resin'\n",
+			       ofnode_get_name(node));
+			device_unbind(dev);
+		}
+	}
+
+	return 0;
+}
+
+static const struct button_ops button_qcom_pmic_ops = {
+	.get_state	= qcom_pwrkey_get_state,
+	.get_code	= qcom_pwrkey_get_code,
+};
+
+static const struct udevice_id qcom_pwrkey_ids[] = {
+	{ .compatible = "qcom,pm8916-pon" },
+	{ .compatible = "qcom,pm8941-pon" },
+	{ .compatible = "qcom,pm8998-pon" },
+	{ }
+};
+
+U_BOOT_DRIVER(qcom_pwrkey) = {
+	.name = "qcom_pwrkey",
+	.id = UCLASS_BUTTON,
+	.of_match = qcom_pwrkey_ids,
+	.bind = button_qcom_pmic_bind,
+	.probe = qcom_pwrkey_probe,
+	.ops = &button_qcom_pmic_ops,
+	.priv_auto = sizeof(struct qcom_pmic_btn_priv),
+};