[PATCH v4 3/4] misc: tps6594-esm: Add driver for TI TPS6594 ESM

[Julien Panis <jpanis@baylibre.com>]

This patch adds support for TPS6594 ESM (Error Signal Monitor).
This device monitors the SoC error output signal at its nERR_SOC input pin.
In error condition, ESM toggles its nRSTOUT_SOC pin to reset the SoC.

Signed-off-by: Julien Panis <jpanis@baylibre.com>
---
 drivers/misc/Kconfig       |  11 ++++
 drivers/misc/Makefile      |   1 +
 drivers/misc/tps6594-esm.c | 132 +++++++++++++++++++++++++++++++++++++
 3 files changed, 144 insertions(+)
 create mode 100644 drivers/misc/tps6594-esm.c

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 433aa4197785..c73c02801330 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -538,6 +538,17 @@ config TMR_INJECT
 
 	  Say N here unless you know what you are doing.
 
+config TPS6594_ESM
+	tristate "TI TPS6594 Error Signal Monitor support"
+	depends on MFD_TPS6594
+	default MFD_TPS6594
+	help
+	  Support ESM (Error Signal Monitor) on TPS6594 PMIC devices.
+	  ESM is used typically to reboot the board in error condition.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called tps6594-esm.
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 56de43943cd5..3dc69ec69912 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -65,3 +65,4 @@ obj-$(CONFIG_GP_PCI1XXXX)	+= mchp_pci1xxxx/
 obj-$(CONFIG_VCPU_STALL_DETECTOR)	+= vcpu_stall_detector.o
 obj-$(CONFIG_TMR_MANAGER)      += xilinx_tmr_manager.o
 obj-$(CONFIG_TMR_INJECT)	+= xilinx_tmr_inject.o
+obj-$(CONFIG_TPS6594_ESM)	+= tps6594-esm.o
diff --git a/drivers/misc/tps6594-esm.c b/drivers/misc/tps6594-esm.c
new file mode 100644
index 000000000000..7dc7cd0697ff
--- /dev/null
+++ b/drivers/misc/tps6594-esm.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ESM (Error Signal Monitor) driver for TI TPS6594/TPS6593/LP8764X PMICs
+ *
+ * Copyright (C) 2023 BayLibre Incorporated - https://www.baylibre.com/
+ */
+
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+
+#include <linux/mfd/tps6594.h>
+
+static irqreturn_t tps6594_esm_isr(int irq, void *dev_id)
+{
+	struct platform_device *pdev = dev_id;
+	int i;
+
+	for (i = 0 ; i < pdev->num_resources ; i++) {
+		if (irq == platform_get_irq_byname(pdev, pdev->resource[i].name)) {
+			dev_err(pdev->dev.parent, "%s error detected\n", pdev->resource[i].name);
+			return IRQ_HANDLED;
+		}
+	}
+
+	return IRQ_NONE;
+}
+
+static int tps6594_esm_probe(struct platform_device *pdev)
+{
+	struct tps6594 *tps = dev_get_drvdata(pdev->dev.parent);
+	struct device *dev = &pdev->dev;
+	int irq;
+	int ret;
+	int i;
+
+	for (i = 0 ; i < pdev->num_resources ; i++) {
+		irq = platform_get_irq_byname(pdev, pdev->resource[i].name);
+		if (irq < 0)
+			return dev_err_probe(dev, irq, "Failed to get %s irq\n",
+					     pdev->resource[i].name);
+
+		ret = devm_request_threaded_irq(dev, irq, NULL,
+						tps6594_esm_isr, IRQF_ONESHOT,
+						pdev->resource[i].name, pdev);
+		if (ret)
+			return dev_err_probe(dev, ret, "Failed to request irq\n");
+	}
+
+	ret = regmap_set_bits(tps->regmap, TPS6594_REG_ESM_SOC_MODE_CFG,
+			      TPS6594_BIT_ESM_SOC_EN | TPS6594_BIT_ESM_SOC_ENDRV);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to configure ESM\n");
+
+	ret = regmap_set_bits(tps->regmap, TPS6594_REG_ESM_SOC_START_REG,
+			      TPS6594_BIT_ESM_SOC_START);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to start ESM\n");
+
+	pm_runtime_enable(dev);
+	pm_runtime_get_sync(dev);
+
+	return 0;
+}
+
+static int tps6594_esm_remove(struct platform_device *pdev)
+{
+	struct tps6594 *tps = dev_get_drvdata(pdev->dev.parent);
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	ret = regmap_clear_bits(tps->regmap, TPS6594_REG_ESM_SOC_START_REG,
+				TPS6594_BIT_ESM_SOC_START);
+	if (ret) {
+		dev_err(dev, "Failed to stop ESM\n");
+		goto out;
+	}
+
+	ret = regmap_clear_bits(tps->regmap, TPS6594_REG_ESM_SOC_MODE_CFG,
+				TPS6594_BIT_ESM_SOC_EN | TPS6594_BIT_ESM_SOC_ENDRV);
+	if (ret)
+		dev_err(dev, "Failed to unconfigure ESM\n");
+
+out:
+	pm_runtime_put_sync(dev);
+	pm_runtime_disable(dev);
+
+	return ret;
+}
+
+static int tps6594_esm_suspend(struct device *dev)
+{
+	struct tps6594 *tps = dev_get_drvdata(dev->parent);
+	int ret;
+
+	ret = regmap_clear_bits(tps->regmap, TPS6594_REG_ESM_SOC_START_REG,
+				TPS6594_BIT_ESM_SOC_START);
+
+	pm_runtime_put_sync(dev);
+
+	return ret;
+}
+
+static int tps6594_esm_resume(struct device *dev)
+{
+	struct tps6594 *tps = dev_get_drvdata(dev->parent);
+
+	pm_runtime_get_sync(dev);
+
+	return regmap_set_bits(tps->regmap, TPS6594_REG_ESM_SOC_START_REG,
+			       TPS6594_BIT_ESM_SOC_START);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(tps6594_esm_pm_ops, tps6594_esm_suspend, tps6594_esm_resume);
+
+static struct platform_driver tps6594_esm_driver = {
+	.driver	= {
+		.name = "tps6594-esm",
+		.pm = pm_sleep_ptr(&tps6594_esm_pm_ops),
+	},
+	.probe = tps6594_esm_probe,
+	.remove = tps6594_esm_remove,
+};
+
+module_platform_driver(tps6594_esm_driver);
+
+MODULE_ALIAS("platform:tps6594-esm");
+MODULE_AUTHOR("Julien Panis <jpanis@baylibre.com>");
+MODULE_DESCRIPTION("TPS6594 Error Signal Monitor Driver");
+MODULE_LICENSE("GPL");
-- 
2.37.3