clk: qcom: Add APCS clock controller support

Add a driver for the 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. It can choose between a
fixed-rate clock or the dedicated APCS (A53) PLL. The source and the
divider can be set both at the same time.

This is required for enabling CPU frequency scaling on MSM8916-based
platforms.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Tested-by: Amit Kucheria <amit.kucheria@linaro.org>
[sboyd@codeaurora.org: Include rcg header for parent_map, drop
multiple unneeded includes, add COMPILE_TEST to APCS depends,
made tristate/modular]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

1 files changed, 138 insertions, 0 deletions

diff --git a/drivers/clk/qcom/apcs-msm8916.c b/drivers/clk/qcom/apcs-msm8916.c
new file mode 100644
index 000000000000..246957f1a413
--- /dev/null
+++ b/drivers/clk/qcom/apcs-msm8916.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Qualcomm APCS clock controller driver
+ *
+ * Copyright (c) 2017, Linaro Limited
+ * Author: Georgi Djakov <georgi.djakov@linaro.org>
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include "clk-regmap.h"
+#include "clk-regmap-mux-div.h"
+
+static const u32 gpll0_a53cc_map[] = { 4, 5 };
+
+static const char * const gpll0_a53cc[] = {
+	"gpll0_vote",
+	"a53pll",
+};
+
+/*
+ * We use the notifier function for switching to a temporary safe configuration
+ * (mux and divider), while the A53 PLL is reconfigured.
+ */
+static int a53cc_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, 4, 3);
+
+	return notifier_from_errno(ret);
+}
+
+static int qcom_apcs_msm8916_clk_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device *parent = dev->parent;
+	struct clk_regmap_mux_div *a53cc;
+	struct regmap *regmap;
+	struct clk_init_data init = { };
+	int ret;
+
+	regmap = dev_get_regmap(parent, NULL);
+	if (IS_ERR(regmap)) {
+		ret = PTR_ERR(regmap);
+		dev_err(dev, "failed to get regmap: %d\n", ret);
+		return ret;
+	}
+
+	a53cc = devm_kzalloc(dev, sizeof(*a53cc), GFP_KERNEL);
+	if (!a53cc)
+		return -ENOMEM;
+
+	init.name = "a53mux";
+	init.parent_names = gpll0_a53cc;
+	init.num_parents = ARRAY_SIZE(gpll0_a53cc);
+	init.ops = &clk_regmap_mux_div_ops;
+	init.flags = CLK_SET_RATE_PARENT;
+
+	a53cc->clkr.hw.init = &init;
+	a53cc->clkr.regmap = regmap;
+	a53cc->reg_offset = 0x50;
+	a53cc->hid_width = 5;
+	a53cc->hid_shift = 0;
+	a53cc->src_width = 3;
+	a53cc->src_shift = 8;
+	a53cc->parent_map = gpll0_a53cc_map;
+
+	a53cc->pclk = devm_clk_get(parent, NULL);
+	if (IS_ERR(a53cc->pclk)) {
+		ret = PTR_ERR(a53cc->pclk);
+		dev_err(dev, "failed to get clk: %d\n", ret);
+		return ret;
+	}
+
+	a53cc->clk_nb.notifier_call = a53cc_notifier_cb;
+	ret = clk_notifier_register(a53cc->pclk, &a53cc->clk_nb);
+	if (ret) {
+		dev_err(dev, "failed to register clock notifier: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_clk_register_regmap(dev, &a53cc->clkr);
+	if (ret) {
+		dev_err(dev, "failed to register regmap clock: %d\n", ret);
+		goto err;
+	}
+
+	ret = of_clk_add_hw_provider(parent->of_node, of_clk_hw_simple_get,
+				     &a53cc->clkr.hw);
+	if (ret) {
+		dev_err(dev, "failed to add clock provider: %d\n", ret);
+		goto err;
+	}
+
+	platform_set_drvdata(pdev, a53cc);
+
+	return 0;
+
+err:
+	clk_notifier_unregister(a53cc->pclk, &a53cc->clk_nb);
+	return ret;
+}
+
+static int qcom_apcs_msm8916_clk_remove(struct platform_device *pdev)
+{
+	struct clk_regmap_mux_div *a53cc = platform_get_drvdata(pdev);
+	struct device *parent = pdev->dev.parent;
+
+	clk_notifier_unregister(a53cc->pclk, &a53cc->clk_nb);
+	of_clk_del_provider(parent->of_node);
+
+	return 0;
+}
+
+static struct platform_driver qcom_apcs_msm8916_clk_driver = {
+	.probe = qcom_apcs_msm8916_clk_probe,
+	.remove = qcom_apcs_msm8916_clk_remove,
+	.driver = {
+		.name = "qcom-apcs-msm8916-clk",
+	},
+};
+module_platform_driver(qcom_apcs_msm8916_clk_driver);
+
+MODULE_AUTHOR("Georgi Djakov <georgi.djakov@linaro.org>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Qualcomm MSM8916 APCS clock driver");