[PATCH v6 3/7] soc: qcom: add QCOM PBS driver

[Anjelique Melendez]

Add the Qualcomm PBS (Programmable Boot Sequencer) driver. The QCOM PBS
driver supports configuring software PBS trigger events through PBS RAM
on Qualcomm Technologies, Inc (QTI) PMICs.

Signed-off-by: Anjelique Melendez <quic_amelende@xxxxxxxxxxx>
---
 drivers/soc/qcom/Kconfig          |   9 ++
 drivers/soc/qcom/Makefile         |   1 +
 drivers/soc/qcom/qcom-pbs.c       | 243 ++++++++++++++++++++++++++++++
 include/linux/soc/qcom/qcom-pbs.h |  30 ++++
 4 files changed, 283 insertions(+)
 create mode 100644 drivers/soc/qcom/qcom-pbs.c
 create mode 100644 include/linux/soc/qcom/qcom-pbs.h

diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index 715348869d04..4f6655b2cb39 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -291,4 +291,13 @@ config QCOM_INLINE_CRYPTO_ENGINE
 	tristate
 	select QCOM_SCM
 
+config QCOM_PBS
+        tristate "PBS trigger support for Qualcomm Technologies, Inc. PMICS"
+        depends on SPMI
+        help
+          This driver supports configuring software programmable boot sequencer (PBS)
+          trigger event through PBS RAM on Qualcomm Technologies, Inc. PMICs.
+          This module provides the APIs to the client drivers that wants to send the
+          PBS trigger event to the PBS RAM.
+
 endmenu
diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
index bbca2e1e55bb..49bb86b0fe33 100644
--- a/drivers/soc/qcom/Makefile
+++ b/drivers/soc/qcom/Makefile
@@ -32,3 +32,4 @@ obj-$(CONFIG_QCOM_KRYO_L2_ACCESSORS) +=	kryo-l2-accessors.o
 obj-$(CONFIG_QCOM_ICC_BWMON)	+= icc-bwmon.o
 qcom_ice-objs			+= ice.o
 obj-$(CONFIG_QCOM_INLINE_CRYPTO_ENGINE)	+= qcom_ice.o
+obj-$(CONFIG_QCOM_PBS) +=	qcom-pbs.o
diff --git a/drivers/soc/qcom/qcom-pbs.c b/drivers/soc/qcom/qcom-pbs.c
new file mode 100644
index 000000000000..b49d14bb7d08
--- /dev/null
+++ b/drivers/soc/qcom/qcom-pbs.c
@@ -0,0 +1,243 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/of_platform.h>
+#include <linux/regmap.h>
+#include <linux/spmi.h>
+#include <linux/soc/qcom/qcom-pbs.h>
+
+#define PBS_CLIENT_TRIG_CTL		0x42
+#define PBS_CLIENT_SW_TRIG_BIT		BIT(7)
+#define PBS_CLIENT_SCRATCH1		0x50
+#define PBS_CLIENT_SCRATCH2		0x51
+#define PBS_CLIENT_SCRATCH2_ERROR	0xFF
+
+struct pbs_dev {
+	struct device		*dev;
+	struct regmap		*regmap;
+	struct mutex		lock;
+	struct device_link	*link;
+
+	u32			base;
+};
+
+static int qcom_pbs_wait_for_ack(struct pbs_dev *pbs, u8 bit_pos)
+{
+	int ret, retries = 2000, delay = 1100;
+	unsigned int val;
+
+	ret = regmap_read_poll_timeout(pbs->regmap,  pbs->base + PBS_CLIENT_SCRATCH2,
+					val, val & BIT(bit_pos), delay, delay * retries);
+
+	if (ret < 0) {
+		dev_err(pbs->dev, "Timeout for PBS ACK/NACK for bit %u\n", bit_pos);
+		return -ETIMEDOUT;
+	}
+
+	if (val == PBS_CLIENT_SCRATCH2_ERROR) {
+		ret = regmap_write(pbs->regmap, pbs->base + PBS_CLIENT_SCRATCH2, 0);
+		dev_err(pbs->dev, "NACK from PBS for bit %u\n", bit_pos);
+		return -EINVAL;
+	}
+
+	dev_dbg(pbs->dev, "PBS sequence for bit %u executed!\n", bit_pos);
+	return 0;
+}
+
+/**
+ * qcom_pbs_trigger_event() - Trigger the PBS RAM sequence
+ * @pbs: Pointer to PBS device
+ * @bitmap: bitmap
+ *
+ * This function is used to trigger the PBS RAM sequence to be
+ * executed by the client driver.
+ *
+ * The PBS trigger sequence involves
+ * 1. setting the PBS sequence bit in PBS_CLIENT_SCRATCH1
+ * 2. Initiating the SW PBS trigger
+ * 3. Checking the equivalent bit in PBS_CLIENT_SCRATCH2 for the
+ *    completion of the sequence.
+ * 4. If PBS_CLIENT_SCRATCH2 == 0xFF, the PBS sequence failed to execute
+ *
+ * Returns: 0 on success, < 0 on failure
+ */
+int qcom_pbs_trigger_event(struct pbs_dev *pbs, u8 bitmap)
+{
+	unsigned int val;
+	u16 bit_pos;
+	int ret;
+
+	if (!bitmap) {
+		dev_err(pbs->dev, "Invalid bitmap passed by client\n");
+		return -EINVAL;
+	}
+
+	if (IS_ERR_OR_NULL(pbs))
+		return -EINVAL;
+
+	mutex_lock(&pbs->lock);
+	ret = regmap_read(pbs->regmap, pbs->base + PBS_CLIENT_SCRATCH2, &val);
+	if (ret < 0)
+		goto out;
+
+	if (val == PBS_CLIENT_SCRATCH2_ERROR) {
+		/* PBS error - clear SCRATCH2 register */
+		ret = regmap_write(pbs->regmap, pbs->base + PBS_CLIENT_SCRATCH2, 0);
+		if (ret < 0)
+			goto out;
+	}
+
+	for (bit_pos = 0; bit_pos < 8; bit_pos++) {
+		if (!(bitmap & BIT(bit_pos)))
+			continue;
+
+		/* Clear the PBS sequence bit position */
+		ret = regmap_update_bits(pbs->regmap, pbs->base + PBS_CLIENT_SCRATCH2,
+					BIT(bit_pos), 0);
+		if (ret < 0)
+			goto error;
+
+		/* Set the PBS sequence bit position */
+		ret = regmap_update_bits(pbs->regmap, pbs->base + PBS_CLIENT_SCRATCH1,
+					BIT(bit_pos), BIT(bit_pos));
+		if (ret < 0)
+			goto error;
+
+		/* Initiate the SW trigger */
+		ret = regmap_update_bits(pbs->regmap, pbs->base + PBS_CLIENT_TRIG_CTL,
+					PBS_CLIENT_SW_TRIG_BIT, PBS_CLIENT_SW_TRIG_BIT);
+		if (ret < 0)
+			goto error;
+
+		ret = qcom_pbs_wait_for_ack(pbs, bit_pos);
+		if (ret < 0)
+			goto error;
+
+		/* Clear the PBS sequence bit position */
+		ret = regmap_update_bits(pbs->regmap, pbs->base + PBS_CLIENT_SCRATCH1,
+					BIT(bit_pos), 0);
+		if (ret < 0)
+			goto error;
+
+		/* Clear the PBS sequence bit position */
+		ret = regmap_update_bits(pbs->regmap, pbs->base + PBS_CLIENT_SCRATCH2,
+					BIT(bit_pos), 0);
+		if (ret < 0)
+			goto error;
+	}
+
+error:
+	/* Clear all the requested bitmap */
+	ret = regmap_update_bits(pbs->regmap, pbs->base + PBS_CLIENT_SCRATCH1, bitmap, 0);
+
+out:
+	mutex_unlock(&pbs->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(qcom_pbs_trigger_event);
+
+/**
+ * get_pbs_client_device() - Get the PBS device used by client
+ * @dev: Client device
+ *
+ * This function is used to get the PBS device that is being
+ * used by the client.
+ *
+ * Returns: pbs_dev on success, ERR_PTR on failure
+ */
+struct pbs_dev *get_pbs_client_device(struct device *dev)
+{
+	struct device_node *pbs_dev_node;
+	struct platform_device *pdev;
+	struct pbs_dev *pbs;
+
+	pbs_dev_node = of_parse_phandle(dev->of_node, "qcom,pbs", 0);
+	if (!pbs_dev_node) {
+		dev_err(dev, "Missing qcom,pbs property\n");
+		return ERR_PTR(-ENODEV);
+	}
+
+	pdev = of_find_device_by_node(pbs_dev_node);
+	if (!pdev) {
+		dev_err(dev, "Unable to find PBS dev_node\n");
+		pbs = ERR_PTR(-EPROBE_DEFER);
+		goto out;
+	}
+
+	pbs = platform_get_drvdata(pdev);
+	if (!pbs) {
+		dev_err(dev, "Cannot get pbs instance from %s\n", dev_name(&pdev->dev));
+		platform_device_put(pdev);
+		pbs = ERR_PTR(-EPROBE_DEFER);
+		goto out;
+	}
+
+	pbs->link = device_link_add(dev, &pdev->dev, DL_FLAG_AUTOREMOVE_SUPPLIER);
+	if (!pbs->link) {
+		dev_err(&pdev->dev, "Failed to create device link to consumer %s\n", dev_name(dev));
+		platform_device_put(pdev);
+		pbs = ERR_PTR(-EINVAL);
+		goto out;
+	}
+
+out:
+	of_node_put(pbs_dev_node);
+	return pbs;
+}
+EXPORT_SYMBOL_GPL(get_pbs_client_device);
+
+static int qcom_pbs_probe(struct platform_device *pdev)
+{
+	struct pbs_dev *pbs;
+	u32 val;
+	int ret;
+
+	pbs = devm_kzalloc(&pdev->dev, sizeof(*pbs), GFP_KERNEL);
+	if (!pbs)
+		return -ENOMEM;
+
+	pbs->dev = &pdev->dev;
+	pbs->regmap = dev_get_regmap(pbs->dev->parent, NULL);
+	if (!pbs->regmap) {
+		dev_err(pbs->dev, "Couldn't get parent's regmap\n");
+		return -EINVAL;
+	}
+
+	ret = device_property_read_u32(pbs->dev, "reg", &val);
+	if (ret < 0) {
+		dev_err(pbs->dev, "Couldn't find reg, ret = %d\n", ret);
+		return ret;
+	}
+	pbs->base = val;
+	mutex_init(&pbs->lock);
+
+	platform_set_drvdata(pdev, pbs);
+
+	return 0;
+}
+
+static const struct of_device_id qcom_pbs_match_table[] = {
+	{ .compatible = "qcom,pbs" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, qcom_pbs_match_table);
+
+static struct platform_driver qcom_pbs_driver = {
+	.driver = {
+		.name		= "qcom-pbs",
+		.of_match_table	= qcom_pbs_match_table,
+	},
+	.probe = qcom_pbs_probe,
+};
+module_platform_driver(qcom_pbs_driver)
+
+MODULE_DESCRIPTION("QCOM PBS DRIVER");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/soc/qcom/qcom-pbs.h b/include/linux/soc/qcom/qcom-pbs.h
new file mode 100644
index 000000000000..8a46209ccf13
--- /dev/null
+++ b/include/linux/soc/qcom/qcom-pbs.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#ifndef _QCOM_PBS_H
+#define _QCOM_PBS_H
+
+#include <linux/errno.h>
+#include <linux/types.h>
+
+struct device_node;
+struct pbs_dev;
+
+#if IS_ENABLED(CONFIG_QCOM_PBS)
+int qcom_pbs_trigger_event(struct pbs_dev *pbs, u8 bitmap);
+struct pbs_dev *get_pbs_client_device(struct device *client_dev);
+#else
+static inline int qcom_pbs_trigger_event(struct pbs_dev *pbs, u8 bitmap)
+{
+	return -ENODEV;
+}
+
+static inline struct pbs_dev *get_pbs_client_device(struct device *client_dev)
+{
+	return ERR_PTR(-ENODEV);
+}
+#endif
+
+#endif
-- 
2.41.0