[v4,16/20] clk: add support for clocks provided by SCMI

diff --git a/MAINTAINERS b/MAINTAINERS
index 8ee63627f1ac..1f9004d68ad4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12954,7 +12954,7 @@  M:	Sudeep Holla <sudeep.holla@arm.com>
 L:	linux-arm-kernel@lists.infradead.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/arm/arm,sc[mp]i.txt
-F:	drivers/clk/clk-scpi.c
+F:	drivers/clk/clk-sc[mp]i.c
 F:	drivers/cpufreq/scpi-cpufreq.c
 F:	drivers/firmware/arm_scpi.c
 F:	drivers/firmware/arm_scmi/
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 1c4e1aa6767e..57c66b22eab8 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -62,6 +62,16 @@  config COMMON_CLK_HI655X
 	  multi-function device has one fixed-rate oscillator, clocked
 	  at 32KHz.
 
+config COMMON_CLK_SCMI
+	tristate "Clock driver controlled via SCMI interface"
+	depends on ARM_SCMI_PROTOCOL || COMPILE_TEST
+	  ---help---
+	  This driver provides support for clocks that are controlled
+	  by firmware that implements the SCMI interface.
+
+	  This driver uses SCMI Message Protocol to interact with the
+	  firmware providing all the clock controls.
+
 config COMMON_CLK_SCPI
 	tristate "Clock driver controlled via SCPI interface"
 	depends on ARM_SCPI_PROTOCOL || COMPILE_TEST
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index c99f363826f0..46ad2f2b686a 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -39,6 +39,7 @@  obj-$(CONFIG_CLK_QORIQ)			+= clk-qoriq.o
 obj-$(CONFIG_COMMON_CLK_RK808)		+= clk-rk808.o
 obj-$(CONFIG_COMMON_CLK_HI655X)		+= clk-hi655x.o
 obj-$(CONFIG_COMMON_CLK_S2MPS11)	+= clk-s2mps11.o
+obj-$(CONFIG_COMMON_CLK_SCMI)           += clk-scmi.o
 obj-$(CONFIG_COMMON_CLK_SCPI)           += clk-scpi.o
 obj-$(CONFIG_COMMON_CLK_SI5351)		+= clk-si5351.o
 obj-$(CONFIG_COMMON_CLK_SI514)		+= clk-si514.o
diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
new file mode 100644
index 000000000000..1e4d7a57779b
--- /dev/null
+++ b/drivers/clk/clk-scmi.c
@@ -0,0 +1,213 @@ 
+/*
+ * System Control and Power Interface (SCMI) Protocol based clock driver
+ *
+ * Copyright (C) 2017 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/module.h>
+#include <linux/scmi_protocol.h>
+#include <asm/div64.h>
+
+struct scmi_clk {
+	u32 id;
+	struct clk_hw hw;
+	const struct scmi_clock_info *info;
+	const struct scmi_handle *handle;
+};
+
+#define to_scmi_clk(clk) container_of(clk, struct scmi_clk, hw)
+
+static unsigned long scmi_clk_recalc_rate(struct clk_hw *hw,
+					  unsigned long parent_rate)
+{
+	int ret;
+	u64 rate;
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	ret = clk->handle->clk_ops->rate_get(clk->handle, clk->id, &rate);
+	if (ret)
+		return 0;
+	return rate;
+}
+
+static long scmi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long *parent_rate)
+{
+	int step;
+	u64 fmin, fmax, ftmp;
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	/*
+	 * We can't figure out what rate it will be, so just return the
+	 * rate back to the caller. scmi_clk_recalc_rate() will be called
+	 * after the rate is set and we'll know what rate the clock is
+	 * running at then.
+	 */
+	if (clk->info->rate_discrete)
+		return rate;
+
+	fmin = clk->info->range.min_rate;
+	fmax = clk->info->range.max_rate;
+	if (rate <= fmin)
+		return fmin;
+	else if (rate >= fmax)
+		return fmax;
+
+	ftmp = rate - fmin;
+	ftmp += clk->info->range.step_size - 1; /* to round up */
+	step = do_div(ftmp, clk->info->range.step_size);
+
+	return step * clk->info->range.step_size + fmin;
+}
+
+static int scmi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+			     unsigned long parent_rate)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	return clk->handle->clk_ops->rate_set(clk->handle, clk->id, 0, rate);
+}
+
+static int scmi_clk_enable(struct clk_hw *hw)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	return clk->handle->clk_ops->enable(clk->handle, clk->id);
+}
+
+static void scmi_clk_disable(struct clk_hw *hw)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+
+	clk->handle->clk_ops->disable(clk->handle, clk->id);
+}
+
+static const struct clk_ops scmi_clk_ops = {
+	.recalc_rate = scmi_clk_recalc_rate,
+	.round_rate = scmi_clk_round_rate,
+	.set_rate = scmi_clk_set_rate,
+	/*
+	 * We can't provide enable/disable callback as we can't perform the same
+	 * in atomic context. Since the clock framework provides standard API
+	 * clk_prepare_enable that helps cases using clk_enable in non-atomic
+	 * context, it should be fine providing prepare/unprepare.
+	 */
+	.prepare = scmi_clk_enable,
+	.unprepare = scmi_clk_disable,
+};
+
+static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk)
+{
+	int ret;
+	struct clk_init_data init = {
+		.flags = CLK_GET_RATE_NOCACHE,
+		.num_parents = 0,
+		.ops = &scmi_clk_ops,
+		.name = sclk->info->name,
+	};
+
+	sclk->hw.init = &init;
+	ret = devm_clk_hw_register(dev, &sclk->hw);
+	if (!ret)
+		clk_hw_set_rate_range(&sclk->hw, sclk->info->range.min_rate,
+				      sclk->info->range.max_rate);
+	return ret;
+}
+
+static int scmi_clocks_probe(struct scmi_device *sdev)
+{
+	int idx, count, err;
+	struct clk_hw **hws;
+	struct clk_hw_onecell_data *clk_data;
+	struct device *dev = &sdev->dev;
+	struct device_node *np = dev->of_node;
+	const struct scmi_handle *handle = sdev->handle;
+
+	if (!handle || !handle->clk_ops)
+		return -ENODEV;
+
+	count = handle->clk_ops->count_get(handle);
+	if (count < 0) {
+		dev_err(dev, "%s: invalid clock output count\n", np->name);
+		return -EINVAL;
+	}
+
+	clk_data = devm_kzalloc(dev, sizeof(*clk_data) +
+				sizeof(*clk_data->hws) * count, GFP_KERNEL);
+	if (!clk_data)
+		return -ENOMEM;
+
+	clk_data->num = count;
+	hws = clk_data->hws;
+
+	for (idx = 0; idx < count; idx++) {
+		struct scmi_clk *sclk;
+
+		sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
+		if (!sclk)
+			return -ENOMEM;
+
+		sclk->info = handle->clk_ops->info_get(handle, idx);
+		if (!sclk->info) {
+			dev_dbg(dev, "invalid clock info for idx %d\n", idx);
+			continue;
+		}
+
+		sclk->id = idx;
+		sclk->handle = handle;
+
+		err = scmi_clk_ops_init(dev, sclk);
+		if (err) {
+			dev_err(dev, "failed to register clock %d\n", idx);
+			devm_kfree(dev, sclk);
+			hws[idx] = NULL;
+		} else {
+			dev_dbg(dev, "Registered clock:%s\n", sclk->info->name);
+			hws[idx] = &sclk->hw;
+		}
+	}
+
+	return of_clk_add_hw_provider(np, of_clk_hw_onecell_get, clk_data);
+}
+
+static void scmi_clocks_remove(struct scmi_device *sdev)
+{
+	struct device *dev = &sdev->dev;
+	struct device_node *np = dev->of_node;
+
+	of_clk_del_provider(np);
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+	{ SCMI_PROTOCOL_CLOCK },
+	{ },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_clocks_driver = {
+	.name = "scmi-clocks",
+	.probe = scmi_clocks_probe,
+	.remove = scmi_clocks_remove,
+	.id_table = scmi_id_table,
+};
+module_scmi_driver(scmi_clocks_driver);
+
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCMI clock driver");
+MODULE_LICENSE("GPL v2");