From 3b36b38f50cc3063f922db629f529b11ff92332b Mon Sep 17 00:00:00 2001
From: Tero Kristo <t-kristo@ti.com>
Date: Fri, 14 Feb 2020 11:18:16 +0200
Subject: [PATCH] misc: pmic_esm: Add support for PMIC ESM driver

The ESM (Error Signal Monitor) is used on certain PMIC versions to
handle error signals propagating from rest of the system. If these
reach the PMIC, it is typically a last resort fatal error which
requires a system reset. The ESM driver does the proper configuration
for the ESM module to reach this end goal. Initially, only TPS65941
PMIC is supported for this.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
---
 doc/device-tree-bindings/misc/esm-pmic.txt | 19 ++++++++
 drivers/misc/Kconfig                       |  7 +++
 drivers/misc/Makefile                      |  1 +
 drivers/misc/esm_pmic.c                    | 69 ++++++++++++++++++++++++++++++
 4 files changed, 96 insertions(+)
 create mode 100644 doc/device-tree-bindings/misc/esm-pmic.txt
 create mode 100644 drivers/misc/esm_pmic.c

diff --git a/doc/device-tree-bindings/misc/esm-pmic.txt b/doc/device-tree-bindings/misc/esm-pmic.txt
new file mode 100644
index 0000000..a60ad74
--- /dev/null
+++ b/doc/device-tree-bindings/misc/esm-pmic.txt
@@ -0,0 +1,19 @@
+PMIC ESM Binding
+======================
+
+Certain Power Management ICs contain safety handling logic within them,
+allowing automatic reset of the board in case a safety error is signaled.
+For this purpose, ESM (Error Signal Monitor) is implemented within
+the PMIC running its own state machine.
+
+Required properties :
+- compatible	: "ti,tps659413-esm"
+
+Example
+=======
+
+&tps659413a {
+	esm: esm {
+		compatible = "ti,tps659413-esm";
+	};
+};
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 38588b2..7664027 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -486,4 +486,11 @@ config K3_AVS0
 	  optimized voltage from the efuse, so that it can be programmed
 	  to the PMIC on board.
 
+config ESM_PMIC
+	bool "Enable PMIC ESM driver"
+	depends on DM_PMIC
+	help
+	  Support ESM (Error Signal Monitor) on PMIC devices. ESM is used
+	  typically to reboot the board in error condition.
+
 endmenu
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 60406c3..68e0e7a 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -73,3 +73,4 @@ obj-$(CONFIG_JZ4780_EFUSE) += jz4780_efuse.o
 obj-$(CONFIG_MICROCHIP_FLEXCOM) += microchip_flexcom.o
 obj-$(CONFIG_K3_AVS0) += k3_avs.o
 obj-$(CONFIG_ESM_K3) += k3_esm.o
+obj-$(CONFIG_ESM_PMIC) += esm_pmic.o
diff --git a/drivers/misc/esm_pmic.c b/drivers/misc/esm_pmic.c
new file mode 100644
index 0000000..92c8d68
--- /dev/null
+++ b/drivers/misc/esm_pmic.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * PMIC Error Signal Monitor driver
+ *
+ * Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
+ *      Tero Kristo <t-kristo@ti.com>
+ *
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <power/pmic.h>
+#include <dm/device_compat.h>
+
+#define INT_ESM_REG		0x6c
+#define INT_ESM_MASK		0x3f
+
+#define ESM_MCU_START_REG	0x8f
+
+#define ESM_MCU_START		BIT(0)
+
+#define ESM_MCU_MODE_CFG_REG	0x92
+
+#define ESM_MCU_EN		BIT(6)
+#define ESM_MCU_ENDRV		BIT(5)
+
+/**
+ * pmic_esm_probe: configures and enables PMIC ESM functionality
+ *
+ * Configures ESM PMIC support and enables it.
+ */
+static int pmic_esm_probe(struct udevice *dev)
+{
+	int ret;
+
+	ret = pmic_reg_write(dev->parent, INT_ESM_REG, INT_ESM_MASK);
+	if (ret) {
+		dev_err(dev, "clearing ESM irqs failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = pmic_reg_write(dev->parent, ESM_MCU_MODE_CFG_REG,
+			     ESM_MCU_EN | ESM_MCU_ENDRV);
+	if (ret) {
+		dev_err(dev, "setting ESM mode failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = pmic_reg_write(dev->parent, ESM_MCU_START_REG, ESM_MCU_START);
+	if (ret) {
+		dev_err(dev, "starting ESM failed: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct udevice_id pmic_esm_ids[] = {
+	{ .compatible = "ti,tps659413-esm" },
+	{}
+};
+
+U_BOOT_DRIVER(pmic_esm) = {
+	.name = "esm_pmic",
+	.of_match = pmic_esm_ids,
+	.id = UCLASS_MISC,
+	.probe = pmic_esm_probe,
+};
-- 
2.7.4