misc: tps6594-pfsm: Add driver for TI TPS6594 PFSM

This PFSM controls the operational modes of the PMIC:
- STANDBY and LP_STANDBY,
- ACTIVE state,
- MCU_ONLY state,
- RETENTION state, with or without DDR and/or GPIO retention.
Depending on the current operational mode, some voltage domains
remain energized while others can be off.

This PFSM is also used to trigger a firmware update, and provides
R/W access to device registers.

See Documentation/misc-devices/tps6594-pfsm.rst for more
information.

Signed-off-by: Julien Panis <jpanis@baylibre.com>
Message-ID: <20230511095126.105104-5-jpanis@baylibre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 319 insertions, 0 deletions

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index c73c02801330..75e427f124b2 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -549,6 +549,18 @@ config TPS6594_ESM
 	  This driver can also be built as a module.  If so, the module
 	  will be called tps6594-esm.
 
+config TPS6594_PFSM
+	tristate "TI TPS6594 Pre-configurable Finite State Machine support"
+	depends on MFD_TPS6594
+	default MFD_TPS6594
+	help
+	  Support PFSM (Pre-configurable Finite State Machine) on TPS6594 PMIC devices.
+	  These devices integrate a finite state machine engine, which manages the state
+	  of the device during operating state transition.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called tps6594-pfsm.
+
 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 3dc69ec69912..f2a4d1ff65d4 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -66,3 +66,4 @@ 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
+obj-$(CONFIG_TPS6594_PFSM)	+= tps6594-pfsm.o
diff --git a/drivers/misc/tps6594-pfsm.c b/drivers/misc/tps6594-pfsm.c
new file mode 100644
index 000000000000..5223d1580807
--- /dev/null
+++ b/drivers/misc/tps6594-pfsm.c
@@ -0,0 +1,306 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PFSM (Pre-configurable Finite State Machine) driver for TI TPS6594/TPS6593/LP8764 PMICs
+ *
+ * Copyright (C) 2023 BayLibre Incorporated - https://www.baylibre.com/
+ */
+
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/interrupt.h>
+#include <linux/ioctl.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include <linux/mfd/tps6594.h>
+
+#include <linux/tps6594_pfsm.h>
+
+#define TPS6594_STARTUP_DEST_MCU_ONLY_VAL 2
+#define TPS6594_STARTUP_DEST_ACTIVE_VAL   3
+#define TPS6594_STARTUP_DEST_SHIFT	  5
+#define TPS6594_STARTUP_DEST_MCU_ONLY	  (TPS6594_STARTUP_DEST_MCU_ONLY_VAL \
+					   << TPS6594_STARTUP_DEST_SHIFT)
+#define TPS6594_STARTUP_DEST_ACTIVE	  (TPS6594_STARTUP_DEST_ACTIVE_VAL \
+					   << TPS6594_STARTUP_DEST_SHIFT)
+
+/*
+ * To update the PMIC firmware, the user must be able to access
+ * page 0 (user registers) and page 1 (NVM control and configuration).
+ */
+#define TPS6594_PMIC_MAX_POS 0x200
+
+#define TPS6594_FILE_TO_PFSM(f) container_of((f)->private_data, struct tps6594_pfsm, miscdev)
+
+/**
+ * struct tps6594_pfsm - device private data structure
+ *
+ * @miscdev: misc device infos
+ * @regmap:  regmap for accessing the device registers
+ */
+struct tps6594_pfsm {
+	struct miscdevice miscdev;
+	struct regmap *regmap;
+};
+
+static ssize_t tps6594_pfsm_read(struct file *f, char __user *buf,
+				 size_t count, loff_t *ppos)
+{
+	struct tps6594_pfsm *pfsm = TPS6594_FILE_TO_PFSM(f);
+	loff_t pos = *ppos;
+	unsigned int val;
+	int ret;
+	int i;
+
+	if (pos < 0)
+		return -EINVAL;
+	if (pos >= TPS6594_PMIC_MAX_POS)
+		return 0;
+	if (count > TPS6594_PMIC_MAX_POS - pos)
+		count = TPS6594_PMIC_MAX_POS - pos;
+
+	for (i = 0 ; i < count ; i++) {
+		ret = regmap_read(pfsm->regmap, pos + i, &val);
+		if (ret)
+			return ret;
+
+		if (put_user(val, buf + i))
+			return -EFAULT;
+	}
+
+	*ppos = pos + count;
+
+	return count;
+}
+
+static ssize_t tps6594_pfsm_write(struct file *f, const char __user *buf,
+				  size_t count, loff_t *ppos)
+{
+	struct tps6594_pfsm *pfsm = TPS6594_FILE_TO_PFSM(f);
+	loff_t pos = *ppos;
+	char val;
+	int ret;
+	int i;
+
+	if (pos < 0)
+		return -EINVAL;
+	if (pos >= TPS6594_PMIC_MAX_POS || !count)
+		return 0;
+	if (count > TPS6594_PMIC_MAX_POS - pos)
+		count = TPS6594_PMIC_MAX_POS - pos;
+
+	for (i = 0 ; i < count ; i++) {
+		if (get_user(val, buf + i))
+			return -EFAULT;
+
+		ret = regmap_write(pfsm->regmap, pos + i, val);
+		if (ret)
+			return ret;
+	}
+
+	*ppos = pos + count;
+
+	return count;
+}
+
+static int tps6594_pfsm_configure_ret_trig(struct regmap *regmap, u8 gpio_ret, u8 ddr_ret)
+{
+	int ret;
+
+	if (gpio_ret)
+		ret = regmap_set_bits(regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+				      TPS6594_BIT_TRIGGER_I2C(5) | TPS6594_BIT_TRIGGER_I2C(6));
+	else
+		ret = regmap_clear_bits(regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+					TPS6594_BIT_TRIGGER_I2C(5) | TPS6594_BIT_TRIGGER_I2C(6));
+	if (ret)
+		return ret;
+
+	if (ddr_ret)
+		ret = regmap_set_bits(regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+				      TPS6594_BIT_TRIGGER_I2C(7));
+	else
+		ret = regmap_clear_bits(regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+					TPS6594_BIT_TRIGGER_I2C(7));
+
+	return ret;
+}
+
+static long tps6594_pfsm_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
+{
+	struct tps6594_pfsm *pfsm = TPS6594_FILE_TO_PFSM(f);
+	struct pmic_state_opt state_opt;
+	void __user *argp = (void __user *)arg;
+	int ret = -ENOIOCTLCMD;
+
+	switch (cmd) {
+	case PMIC_GOTO_STANDBY:
+		/* Disable LP mode */
+		ret = regmap_clear_bits(pfsm->regmap, TPS6594_REG_RTC_CTRL_2,
+					TPS6594_BIT_LP_STANDBY_SEL);
+		if (ret)
+			return ret;
+
+		/* Force trigger */
+		ret = regmap_write_bits(pfsm->regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+					TPS6594_BIT_TRIGGER_I2C(0), TPS6594_BIT_TRIGGER_I2C(0));
+		break;
+	case PMIC_GOTO_LP_STANDBY:
+		/* Enable LP mode */
+		ret = regmap_set_bits(pfsm->regmap, TPS6594_REG_RTC_CTRL_2,
+				      TPS6594_BIT_LP_STANDBY_SEL);
+		if (ret)
+			return ret;
+
+		/* Force trigger */
+		ret = regmap_write_bits(pfsm->regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+					TPS6594_BIT_TRIGGER_I2C(0), TPS6594_BIT_TRIGGER_I2C(0));
+		break;
+	case PMIC_UPDATE_PGM:
+		/* Force trigger */
+		ret = regmap_write_bits(pfsm->regmap, TPS6594_REG_FSM_I2C_TRIGGERS,
+					TPS6594_BIT_TRIGGER_I2C(3), TPS6594_BIT_TRIGGER_I2C(3));
+		break;
+	case PMIC_SET_ACTIVE_STATE:
+		/* Modify NSLEEP1-2 bits */
+		ret = regmap_set_bits(pfsm->regmap, TPS6594_REG_FSM_NSLEEP_TRIGGERS,
+				      TPS6594_BIT_NSLEEP1B | TPS6594_BIT_NSLEEP2B);
+		break;
+	case PMIC_SET_MCU_ONLY_STATE:
+		if (copy_from_user(&state_opt, argp, sizeof(state_opt)))
+			return -EFAULT;
+
+		/* Configure retention triggers */
+		ret = tps6594_pfsm_configure_ret_trig(pfsm->regmap, state_opt.gpio_retention,
+						      state_opt.ddr_retention);
+		if (ret)
+			return ret;
+
+		/* Modify NSLEEP1-2 bits */
+		ret = regmap_clear_bits(pfsm->regmap, TPS6594_REG_FSM_NSLEEP_TRIGGERS,
+					TPS6594_BIT_NSLEEP1B);
+		if (ret)
+			return ret;
+
+		ret = regmap_set_bits(pfsm->regmap, TPS6594_REG_FSM_NSLEEP_TRIGGERS,
+				      TPS6594_BIT_NSLEEP2B);
+		break;
+	case PMIC_SET_RETENTION_STATE:
+		if (copy_from_user(&state_opt, argp, sizeof(state_opt)))
+			return -EFAULT;
+
+		/* Configure wake-up destination */
+		if (state_opt.mcu_only_startup_dest)
+			ret = regmap_write_bits(pfsm->regmap, TPS6594_REG_RTC_CTRL_2,
+						TPS6594_MASK_STARTUP_DEST,
+						TPS6594_STARTUP_DEST_MCU_ONLY);
+		else
+			ret = regmap_write_bits(pfsm->regmap, TPS6594_REG_RTC_CTRL_2,
+						TPS6594_MASK_STARTUP_DEST,
+						TPS6594_STARTUP_DEST_ACTIVE);
+		if (ret)
+			return ret;
+
+		/* Configure retention triggers */
+		ret = tps6594_pfsm_configure_ret_trig(pfsm->regmap, state_opt.gpio_retention,
+						      state_opt.ddr_retention);
+		if (ret)
+			return ret;
+
+		/* Modify NSLEEP1-2 bits */
+		ret = regmap_clear_bits(pfsm->regmap, TPS6594_REG_FSM_NSLEEP_TRIGGERS,
+					TPS6594_BIT_NSLEEP2B);
+		break;
+	}
+
+	return ret;
+}
+
+static const struct file_operations tps6594_pfsm_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= generic_file_llseek,
+	.read		= tps6594_pfsm_read,
+	.write		= tps6594_pfsm_write,
+	.unlocked_ioctl	= tps6594_pfsm_ioctl,
+	.compat_ioctl   = compat_ptr_ioctl,
+};
+
+static irqreturn_t tps6594_pfsm_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 event detected\n", pdev->resource[i].name);
+			return IRQ_HANDLED;
+		}
+	}
+
+	return IRQ_NONE;
+}
+
+static int tps6594_pfsm_probe(struct platform_device *pdev)
+{
+	struct tps6594_pfsm *pfsm;
+	struct tps6594 *tps = dev_get_drvdata(pdev->dev.parent);
+	struct device *dev = &pdev->dev;
+	int irq;
+	int ret;
+	int i;
+
+	pfsm = devm_kzalloc(dev, sizeof(struct tps6594_pfsm), GFP_KERNEL);
+	if (!pfsm)
+		return -ENOMEM;
+
+	pfsm->regmap = tps->regmap;
+
+	pfsm->miscdev.minor = MISC_DYNAMIC_MINOR;
+	pfsm->miscdev.name = devm_kasprintf(dev, GFP_KERNEL, "pfsm-%ld-0x%02x",
+					    tps->chip_id, tps->reg);
+	pfsm->miscdev.fops = &tps6594_pfsm_fops;
+	pfsm->miscdev.parent = dev->parent;
+
+	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_pfsm_isr, IRQF_ONESHOT,
+						pdev->resource[i].name, pdev);
+		if (ret)
+			return dev_err_probe(dev, ret, "Failed to request irq\n");
+	}
+
+	platform_set_drvdata(pdev, pfsm);
+
+	return misc_register(&pfsm->miscdev);
+}
+
+static int tps6594_pfsm_remove(struct platform_device *pdev)
+{
+	struct tps6594_pfsm *pfsm = platform_get_drvdata(pdev);
+
+	misc_deregister(&pfsm->miscdev);
+
+	return 0;
+}
+
+static struct platform_driver tps6594_pfsm_driver = {
+	.driver	= {
+		.name = "tps6594-pfsm",
+	},
+	.probe = tps6594_pfsm_probe,
+	.remove = tps6594_pfsm_remove,
+};
+
+module_platform_driver(tps6594_pfsm_driver);
+
+MODULE_ALIAS("platform:tps6594-pfsm");
+MODULE_AUTHOR("Julien Panis <jpanis@baylibre.com>");
+MODULE_DESCRIPTION("TPS6594 Pre-configurable Finite State Machine Driver");
+MODULE_LICENSE("GPL");