Date:   Thu, 17 Nov 2022 14:29:56 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     agross@...nel.org
Cc:     andersson@...nel.org, konrad.dybcio@...ainline.org,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        angelogioacchino.delregno@...labora.com,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, marijn.suijten@...ainline.org,
        kernel@...labora.com
Subject: [PATCH v4 2/2] soc: qcom: Add Qualcomm Ramp Controller driver

The Ramp Controller is used to program the sequence ID for pulse
swallowing, enable sequence and linking sequence IDs for the CPU
cores on some Qualcomm SoCs.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
---
 drivers/soc/qcom/Kconfig           |   9 +
 drivers/soc/qcom/Makefile          |   1 +
 drivers/soc/qcom/ramp_controller.c | 342 +++++++++++++++++++++++++++++
 3 files changed, 352 insertions(+)
 create mode 100644 drivers/soc/qcom/ramp_controller.c

diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index 024e420f1bb7..d174183a26f7 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -95,6 +95,15 @@ config QCOM_QMI_HELPERS
 	tristate
 	depends on NET
 
+config QCOM_RAMP_CTRL
+	tristate "Qualcomm Ramp Controller driver"
+	depends on ARCH_QCOM || COMPILE_TEST
+	help
+	  The Ramp Controller is used to program the sequence ID for pulse
+	  swallowing, enable sequence and link sequence IDs for the CPU
+	  cores on some Qualcomm SoCs.
+	  Say y here to enable support for the ramp controller.
+
 config QCOM_RMTFS_MEM
 	tristate "Qualcomm Remote Filesystem memory driver"
 	depends on ARCH_QCOM
diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
index d66604aff2b0..6e02333c4080 100644
--- a/drivers/soc/qcom/Makefile
+++ b/drivers/soc/qcom/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_QCOM_OCMEM)	+= ocmem.o
 obj-$(CONFIG_QCOM_PDR_HELPERS)	+= pdr_interface.o
 obj-$(CONFIG_QCOM_QMI_HELPERS)	+= qmi_helpers.o
 qmi_helpers-y	+= qmi_encdec.o qmi_interface.o
+obj-$(CONFIG_QCOM_RAMP_CTRL)	+= ramp_controller.o
 obj-$(CONFIG_QCOM_RMTFS_MEM)	+= rmtfs_mem.o
 obj-$(CONFIG_QCOM_RPMH)		+= qcom_rpmh.o
 qcom_rpmh-y			+= rpmh-rsc.o
diff --git a/drivers/soc/qcom/ramp_controller.c b/drivers/soc/qcom/ramp_controller.c
new file mode 100644
index 000000000000..8f8c514b7288
--- /dev/null
+++ b/drivers/soc/qcom/ramp_controller.c
@@ -0,0 +1,342 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Qualcomm Ramp Controller driver
+ * Copyright (c) 2022, AngeloGioacchino Del Regno
+ *                     <angelogioacchino.delregno@...labora.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+#define RC_UPDATE_EN		BIT(0)
+#define RC_ROOT_EN		BIT(1)
+
+#define RC_REG_CFG_UPDATE	0x60
+#define RC_CFG_UPDATE_EN	BIT(8)
+#define RC_CFG_ACK		GENMASK(31, 16)
+
+#define RC_DCVS_CFG_SID		2
+#define RC_LINK_SID		3
+#define RC_LMH_SID		6
+#define RC_DFS_SID		14
+
+#define RC_UPDATE_TIMEOUT_US	500
+
+/**
+ * struct qcom_ramp_controller_desc - SoC specific parameters
+ * @cfg_dfs_sid:      Dynamic Frequency Scaling SID configuration
+ * @cfg_link_sid:     Link SID configuration
+ * @cfg_lmh_sid:      Limits Management hardware SID configuration
+ * @cfg_ramp_en:      Ramp Controller enable sequence
+ * @cfg_ramp_dis:     Ramp Controller disable sequence
+ * @cmd_reg:          Command register offset
+ * @num_dfs_sids:     Number of DFS SIDs (max 8)
+ * @num_link_sids:    Number of Link SIDs (max 3)
+ * @num_lmh_sids:     Number of LMh SIDs (max 8)
+ * @num_ramp_en:      Number of entries in enable sequence
+ * @num_ramp_dis:     Number of entries in disable sequence
+ */
+struct qcom_ramp_controller_desc {
+	const struct reg_sequence *cfg_dfs_sid;
+	const struct reg_sequence *cfg_link_sid;
+	const struct reg_sequence *cfg_lmh_sid;
+	const struct reg_sequence *cfg_ramp_en;
+	const struct reg_sequence *cfg_ramp_dis;
+	u8 cmd_reg;
+	u8 num_dfs_sids;
+	u8 num_link_sids;
+	u8 num_lmh_sids;
+	u8 num_ramp_en;
+	u8 num_ramp_dis;
+};
+
+/**
+ * struct qcom_ramp_controller - Main driver structure
+ * @regmap: Regmap handle
+ * @desc:   SoC specific parameters
+ */
+struct qcom_ramp_controller {
+	struct regmap *regmap;
+	const struct qcom_ramp_controller_desc *desc;
+};
+
+/**
+ * rc_wait_for_update() - Wait for Ramp Controller root update
+ * @qrc: Main driver structure
+ *
+ * Return: Zero for success or negative number for failure
+ */
+static int rc_wait_for_update(struct qcom_ramp_controller *qrc)
+{
+	const struct qcom_ramp_controller_desc *d = qrc->desc;
+	struct regmap *r = qrc->regmap;
+	u32 val;
+	int ret;
+
+	ret = regmap_set_bits(r, d->cmd_reg, RC_ROOT_EN);
+	if (ret)
+		return ret;
+
+	return regmap_read_poll_timeout(r, d->cmd_reg, val, !(val & RC_UPDATE_EN),
+					1, RC_UPDATE_TIMEOUT_US);
+}
+
+/**
+ * rc_set_cfg_update() - Ramp Controller configuration update
+ * @qrc: Main driver structure
+ * @ce: Configuration entry to update
+ *
+ * Return: Zero for success or negative number for failure
+ */
+static int rc_set_cfg_update(struct qcom_ramp_controller *qrc, u8 ce)
+{
+	const struct qcom_ramp_controller_desc *d = qrc->desc;
+	struct regmap *r = qrc->regmap;
+	u32 ack, val;
+	int ret;
+
+	/* The ack bit is between bits 16-31 of RC_REG_CFG_UPDATE */
+	ack = FIELD_PREP(RC_CFG_ACK, BIT(ce));
+
+	/* Write the configuration type first... */
+	ret = regmap_set_bits(r, d->cmd_reg + RC_REG_CFG_UPDATE, ce);
+	if (ret)
+		return ret;
+
+	/* ...and after that, enable the update bit to sync the changes */
+	ret = regmap_set_bits(r, d->cmd_reg + RC_REG_CFG_UPDATE, RC_CFG_UPDATE_EN);
+	if (ret)
+		return ret;
+
+	/* Wait for the changes to go through */
+	ret = regmap_read_poll_timeout(r, d->cmd_reg + RC_REG_CFG_UPDATE, val,
+				       val & ack, 1, RC_UPDATE_TIMEOUT_US);
+	if (ret)
+		return ret;
+
+	/*
+	 * Configuration update success! The CFG_UPDATE register will not be
+	 * cleared automatically upon applying the configuration, so we have
+	 * to do that manually in order to leave the ramp controller in a
+	 * predictable and clean state.
+	 */
+	ret = regmap_write(r, d->cmd_reg + RC_REG_CFG_UPDATE, 0);
+	if (ret)
+		return ret;
+
+	/* Wait for the update bit cleared ack */
+	return regmap_read_poll_timeout(r, d->cmd_reg + RC_REG_CFG_UPDATE,
+					val, !(val & RC_CFG_ACK), 1,
+					RC_UPDATE_TIMEOUT_US);
+}
+
+/**
+ * rc_write_cfg - Send configuration sequence
+ * @qrc: Main driver structure
+ * @seq: Register sequence to send before asking for update
+ * @ce: Configuration SID
+ * @nsids: Total number of SIDs
+ *
+ * Returns: Zero for success or negative number for error
+ */
+static int rc_write_cfg(struct qcom_ramp_controller *qrc,
+			const struct reg_sequence *seq,
+			u16 ce, u8 nsids)
+{
+	int ret;
+	u8 i;
+
+	/* Check if, and wait until the ramp controller is ready */
+	ret = rc_wait_for_update(qrc);
+	if (ret)
+		return ret;
+
+	/* Write the sequence */
+	ret = regmap_multi_reg_write(qrc->regmap, seq, nsids);
+	if (ret)
+		return ret;
+
+	/* Pull the trigger: do config update starting from the last sid */
+	for (i = 0; i < nsids; i++) {
+		ret = rc_set_cfg_update(qrc, (u8)ce - i);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * rc_ramp_ctrl_enable() - Enable Ramp up/down Control
+ * @qrc: Main driver structure
+ *
+ * Return: Zero for success or negative number for error
+ */
+static int rc_ramp_ctrl_enable(struct qcom_ramp_controller *qrc)
+{
+	const struct qcom_ramp_controller_desc *d = qrc->desc;
+	int i, ret;
+
+	for (i = 0; i < d->num_ramp_en; i++) {
+		ret = rc_write_cfg(qrc, &d->cfg_ramp_en[i], RC_DCVS_CFG_SID, 1);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * qcom_ramp_controller_start() - Initialize and start the ramp controller
+ * @qrc: Main driver structure
+ *
+ * The Ramp Controller needs to be initialized by programming the relevant
+ * registers with SoC-specific configuration: once programming is done,
+ * the hardware will take care of the rest (no further handling required).
+ *
+ * Return: Zero for success or negative number for error
+ */
+static int qcom_ramp_controller_start(struct qcom_ramp_controller *qrc)
+{
+	const struct qcom_ramp_controller_desc *d = qrc->desc;
+	int ret;
+
+	/* Program LMH, DFS, Link SIDs */
+	ret = rc_write_cfg(qrc, d->cfg_lmh_sid, RC_LMH_SID, d->num_lmh_sids);
+	if (ret)
+		return ret;
+
+	ret = rc_write_cfg(qrc, d->cfg_dfs_sid, RC_DFS_SID, d->num_dfs_sids);
+	if (ret)
+		return ret;
+
+	ret = rc_write_cfg(qrc, d->cfg_link_sid, RC_LINK_SID, d->num_link_sids);
+	if (ret)
+		return ret;
+
+	/* Everything is ready! Enable the ramp up/down control */
+	return rc_ramp_ctrl_enable(qrc);
+}
+
+static const struct regmap_config qrc_regmap_config = {
+	.reg_bits = 32,
+	.reg_stride = 4,
+	.val_bits = 32,
+	.max_register =	0x68,
+	.fast_io = true,
+};
+
+const struct reg_sequence msm8976_cfg_dfs_sid[] = {
+	{ 0x10, 0xfefebff7 },
+	{ 0x14, 0xfdff7fef },
+	{ 0x18, 0xfbffdefb },
+	{ 0x1c, 0xb69b5555 },
+	{ 0x20, 0x24929249 },
+	{ 0x24, 0x49241112 },
+	{ 0x28, 0x11112111 },
+	{ 0x2c, 0x8102 }
+};
+
+const struct reg_sequence msm8976_cfg_link_sid[] = {
+	{ 0x40, 0xfc987 }
+};
+
+const struct reg_sequence msm8976_cfg_lmh_sid[] = {
+	{ 0x30, 0x77706db },
+	{ 0x34, 0x5550249 },
+	{ 0x38, 0x111 }
+};
+
+const struct reg_sequence msm8976_cfg_ramp_en[] = {
+	{ 0x50, 0x800 }, /* pre_en */
+	{ 0x50, 0xc00 }, /* en */
+	{ 0x50, 0x400 }  /* post_en */
+};
+
+const struct reg_sequence msm8976_cfg_ramp_dis[] = {
+	{ 0x50, 0x0 }
+};
+
+static const struct qcom_ramp_controller_desc msm8976_rc_cfg = {
+	.cfg_dfs_sid = msm8976_cfg_dfs_sid,
+	.num_dfs_sids = ARRAY_SIZE(msm8976_cfg_dfs_sid),
+
+	.cfg_link_sid = msm8976_cfg_link_sid,
+	.num_link_sids = ARRAY_SIZE(msm8976_cfg_link_sid),
+
+	.cfg_lmh_sid = msm8976_cfg_lmh_sid,
+	.num_lmh_sids = ARRAY_SIZE(msm8976_cfg_lmh_sid),
+
+	.cfg_ramp_en = msm8976_cfg_ramp_en,
+	.num_ramp_en = ARRAY_SIZE(msm8976_cfg_ramp_en),
+
+	.cfg_ramp_dis = msm8976_cfg_ramp_dis,
+	.num_ramp_dis = ARRAY_SIZE(msm8976_cfg_ramp_dis),
+
+	.cmd_reg = 0x0,
+};
+
+static int qcom_ramp_controller_probe(struct platform_device *pdev)
+{
+	struct qcom_ramp_controller *qrc;
+	void __iomem *base;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	qrc = devm_kmalloc(&pdev->dev, sizeof(*qrc), GFP_KERNEL);
+	if (!qrc)
+		return -ENOMEM;
+
+	qrc->desc = device_get_match_data(&pdev->dev);
+	if (!qrc)
+		return -EINVAL;
+
+	qrc->regmap = devm_regmap_init_mmio(&pdev->dev, base, &qrc_regmap_config);
+	if (IS_ERR(qrc->regmap))
+		return PTR_ERR(qrc->regmap);
+
+	platform_set_drvdata(pdev, qrc);
+
+	return qcom_ramp_controller_start(qrc);
+}
+
+static int qcom_ramp_controller_remove(struct platform_device *pdev)
+{
+	struct qcom_ramp_controller *qrc = platform_get_drvdata(pdev);
+
+	return rc_write_cfg(qrc, qrc->desc->cfg_ramp_dis,
+			    RC_DCVS_CFG_SID, qrc->desc->num_ramp_dis);
+}
+
+static const struct of_device_id qcom_ramp_controller_match_table[] = {
+	{ .compatible = "qcom,msm8976-ramp-controller", .data = &msm8976_rc_cfg },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, qcom_ramp_controller_match_table);
+
+static struct platform_driver qcom_ramp_controller_driver = {
+	.driver = {
+		.name = "qcom-ramp-controller",
+		.of_match_table = qcom_ramp_controller_match_table,
+		.suppress_bind_attrs = true,
+	},
+	.probe  = qcom_ramp_controller_probe,
+	.remove = qcom_ramp_controller_remove,
+};
+
+static int __init qcom_ramp_controller_init(void)
+{
+	return platform_driver_register(&qcom_ramp_controller_driver);
+}
+arch_initcall(qcom_ramp_controller_init);
+
+MODULE_AUTHOR("AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>");
+MODULE_DESCRIPTION("Qualcomm Ramp Controller driver");
+MODULE_LICENSE("GPL");
-- 
2.38.1

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