clk: qcom: Add SDX55 APCS clock controller support

Add a driver for the SDX55 APCS clock controller. It is part of the APCS
hardware block, which among other things implements also a combined mux
and half integer divider functionality. The APCS clock controller has 3
parent clocks:

1. Board XO
2. Fixed rate GPLL0
3. A7 PLL

The source and the divider can be set both at the same time.

This is required for enabling CPU frequency scaling on SDX55-based
platforms.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

3 files changed, 158 insertions, 0 deletions

diff --git a/drivers/clk/qcom/Kconfig b/drivers/clk/qcom/Kconfig
index d6f4aee4427a..2c67fdfae913 100644
--- a/drivers/clk/qcom/Kconfig
+++ b/drivers/clk/qcom/Kconfig
@@ -45,6 +45,15 @@ config QCOM_CLK_APCS_MSM8916
 	  Say Y if you want to support CPU frequency scaling on devices
 	  such as msm8916.
 
+config QCOM_CLK_APCS_SDX55
+	tristate "SDX55 APCS Clock Controller"
+	depends on QCOM_APCS_IPC || COMPILE_TEST
+	help
+	  Support for the APCS Clock Controller on SDX55 platform. The
+	  APCS is managing the mux and divider which feeds the CPUs.
+	  Say Y if you want to support CPU frequency scaling on devices
+	  such as SDX55.
+
 config QCOM_CLK_APCC_MSM8996
 	tristate "MSM8996 CPU Clock Controller"
 	select QCOM_KRYO_L2_ACCESSORS
diff --git a/drivers/clk/qcom/Makefile b/drivers/clk/qcom/Makefile
index e7e0ac382176..a9271f40916c 100644
--- a/drivers/clk/qcom/Makefile
+++ b/drivers/clk/qcom/Makefile
@@ -46,6 +46,7 @@ obj-$(CONFIG_MSM_MMCC_8998) += mmcc-msm8998.o
 obj-$(CONFIG_QCOM_A53PLL) += a53-pll.o
 obj-$(CONFIG_QCOM_A7PLL) += a7-pll.o
 obj-$(CONFIG_QCOM_CLK_APCS_MSM8916) += apcs-msm8916.o
+obj-$(CONFIG_QCOM_CLK_APCS_SDX55) += apcs-sdx55.o
 obj-$(CONFIG_QCOM_CLK_APCC_MSM8996) += clk-cpu-8996.o
 obj-$(CONFIG_QCOM_CLK_RPM) += clk-rpm.o
 obj-$(CONFIG_QCOM_CLK_RPMH) += clk-rpmh.o
diff --git a/drivers/clk/qcom/apcs-sdx55.c b/drivers/clk/qcom/apcs-sdx55.c
new file mode 100644
index 000000000000..8d82be76ef32
--- /dev/null
+++ b/drivers/clk/qcom/apcs-sdx55.c
@@ -0,0 +1,148 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Qualcomm SDX55 APCS clock controller driver
+ *
+ * Copyright (c) 2020, Linaro Limited
+ * Author: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/cpu.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#include "clk-regmap.h"
+#include "clk-regmap-mux-div.h"
+#include "common.h"
+
+static const u32 apcs_mux_clk_parent_map[] = { 0, 1, 5 };
+
+static const struct clk_parent_data pdata[] = {
+	{ .fw_name = "ref", .name = "bi_tcxo", },
+	{ .fw_name = "aux", .name = "gpll0", },
+	{ .fw_name = "pll", .name = "a7pll", },
+};
+
+/*
+ * We use the notifier function for switching to a temporary safe configuration
+ * (mux and divider), while the A7 PLL is reconfigured.
+ */
+static int a7cc_notifier_cb(struct notifier_block *nb, unsigned long event,
+			    void *data)
+{
+	int ret = 0;
+	struct clk_regmap_mux_div *md = container_of(nb,
+						     struct clk_regmap_mux_div,
+						     clk_nb);
+	if (event == PRE_RATE_CHANGE)
+		/* set the mux and divider to safe frequency (400mhz) */
+		ret = mux_div_set_src_div(md, 1, 2);
+
+	return notifier_from_errno(ret);
+}
+static int qcom_apcs_sdx55_clk_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device *parent = dev->parent;
+	struct device *cpu_dev;
+	struct clk_regmap_mux_div *a7cc;
+	struct regmap *regmap;
+	struct clk_init_data init = { };
+	int ret = -ENODEV;
+
+	regmap = dev_get_regmap(parent, NULL);
+	if (!regmap) {
+		dev_err(dev, "Failed to get parent regmap: %d\n", ret);
+		return ret;
+	}
+
+	a7cc = devm_kzalloc(dev, sizeof(*a7cc), GFP_KERNEL);
+	if (!a7cc)
+		return -ENOMEM;
+
+	init.name = "a7mux";
+	init.parent_data = pdata;
+	init.num_parents = ARRAY_SIZE(pdata);
+	init.ops = &clk_regmap_mux_div_ops;
+
+	a7cc->clkr.hw.init = &init;
+	a7cc->clkr.regmap = regmap;
+	a7cc->reg_offset = 0x8;
+	a7cc->hid_width = 5;
+	a7cc->hid_shift = 0;
+	a7cc->src_width = 3;
+	a7cc->src_shift = 8;
+	a7cc->parent_map = apcs_mux_clk_parent_map;
+
+	a7cc->pclk = devm_clk_get(parent, "pll");
+	if (IS_ERR(a7cc->pclk)) {
+		ret = PTR_ERR(a7cc->pclk);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "Failed to get PLL clk: %d\n", ret);
+		return ret;
+	}
+
+	a7cc->clk_nb.notifier_call = a7cc_notifier_cb;
+	ret = clk_notifier_register(a7cc->pclk, &a7cc->clk_nb);
+	if (ret) {
+		dev_err(dev, "Failed to register clock notifier: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_clk_register_regmap(dev, &a7cc->clkr);
+	if (ret) {
+		dev_err(dev, "Failed to register regmap clock: %d\n", ret);
+		goto err;
+	}
+
+	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
+					  &a7cc->clkr.hw);
+	if (ret) {
+		dev_err(dev, "Failed to add clock provider: %d\n", ret);
+		goto err;
+	}
+
+	platform_set_drvdata(pdev, a7cc);
+
+	/*
+	 * Attach the power domain to cpudev. There seems to be no better place
+	 * to do this, so do it here.
+	 */
+	cpu_dev = get_cpu_device(0);
+	dev_pm_domain_attach(cpu_dev, true);
+
+	return 0;
+
+err:
+	clk_notifier_unregister(a7cc->pclk, &a7cc->clk_nb);
+	return ret;
+}
+
+static int qcom_apcs_sdx55_clk_remove(struct platform_device *pdev)
+{
+	struct device *cpu_dev = get_cpu_device(0);
+	struct clk_regmap_mux_div *a7cc = platform_get_drvdata(pdev);
+
+	clk_notifier_unregister(a7cc->pclk, &a7cc->clk_nb);
+	dev_pm_domain_detach(cpu_dev, true);
+
+	return 0;
+}
+
+static struct platform_driver qcom_apcs_sdx55_clk_driver = {
+	.probe = qcom_apcs_sdx55_clk_probe,
+	.remove = qcom_apcs_sdx55_clk_remove,
+	.driver = {
+		.name = "qcom-sdx55-acps-clk",
+	},
+};
+module_platform_driver(qcom_apcs_sdx55_clk_driver);
+
+MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Qualcomm SDX55 APCS clock driver");