[PATCHv2 3/7] misc: pmic_esm: Add support for PMIC ESM driver

[Tero Kristo]

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 at 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 0000000000..a60ad74679
--- /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 38588b2cbd..766402745d 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 60406c3e0a..68e0e7ad17 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 0000000000..92c8d68f7c
--- /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 at 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,
+};
-- 
2.17.1

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