[PATCH v2 4/5] clk: hisi: add stub clk driver

[Leo Yan <leo.yan-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

On hisilicon platform, there have some clocks which can directly send
messages to power controller to change frequency; this includes cpu and
ddr's clocks.

For dynamic frequency scaling, firstly need write the frequency value
to sram region, and then write the communication register to trigger
power controller to run the state machine. These two part's addresses
are different and will be shared w/t other module; so use syscon APIs
to pass these two memory region and accessing related registers.

This init driver will support cpu frequency change firstly.

Signed-off-by: Leo Yan <leo.yan-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 drivers/clk/hisilicon/Makefile              |   2 +-
 drivers/clk/hisilicon/clk-stub.c            | 282 ++++++++++++++++++++++++++++
 drivers/clk/hisilicon/clk.h                 |   3 +
 include/dt-bindings/clock/hisi,stub-clock.h |  26 +++
 4 files changed, 312 insertions(+), 1 deletion(-)
 create mode 100644 drivers/clk/hisilicon/clk-stub.c
 create mode 100644 include/dt-bindings/clock/hisi,stub-clock.h

diff --git a/drivers/clk/hisilicon/Makefile b/drivers/clk/hisilicon/Makefile
index 038c02f..fb26ac8 100644
--- a/drivers/clk/hisilicon/Makefile
+++ b/drivers/clk/hisilicon/Makefile
@@ -2,7 +2,7 @@
 # Hisilicon Clock specific Makefile
 #
 
-obj-y	+= clk.o clkgate-separated.o
+obj-y	+= clk.o clkgate-separated.o clk-stub.o
 
 obj-$(CONFIG_ARCH_HI3xxx)	+= clk-hi3620.o
 obj-$(CONFIG_ARCH_HIP04)	+= clk-hip04.o
diff --git a/drivers/clk/hisilicon/clk-stub.c b/drivers/clk/hisilicon/clk-stub.c
new file mode 100644
index 0000000..5a94192
--- /dev/null
+++ b/drivers/clk/hisilicon/clk-stub.c
@@ -0,0 +1,282 @@
+/*
+ * Hisilicon stub clock driver
+ *
+ * Copyright (c) 2015 Hisilicon Limited.
+ * Copyright (c) 2015 Linaro Limited.
+ *
+ * Author: Leo Yan <leo.yan-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <asm/compiler.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#include <dt-bindings/clock/hisi,stub-clock.h>
+
+/* CPU dynamic frequency scaling */
+#define ACPU_DFS_FREQ_MAX		(0x1724)
+#define ACPU_DFS_FLAG			(0x1AF4)
+#define ACPU_DFS_FREQ_REQ		(0x1AF8)
+#define ACPU_DFS_FREQ_LMT		(0x1AFC)
+
+#define ACPU_DFS_LOCK_FLAG		(0xAEAEAEAE)
+
+/* Multi-core communication */
+#define MC_CORE_ACPU			0x2
+#define MC_COM_CPU_RAW_INT_OFFSET(i)	(0x400 + (i << 4))
+#define MC_COM_INT_ACPU_DFS		15
+
+#define to_stub_clk(hw) container_of(hw, struct hisi_stub_clk, hw)
+
+struct hisi_stub_clk {
+	struct clk_hw	hw;
+
+	/*
+	 * hi6220:
+	 *  - 0: A53; 1: A53;  2: gpu;  3: ddr;
+	 */
+	u32		id;
+	u32		rate;
+	spinlock_t	*lock;
+};
+
+static int initialized_stub_clk = 0;
+static struct regmap *mc_map = NULL;
+static struct regmap *dfs_map = NULL;
+
+static unsigned int hisi_acpu_get_freq(void)
+{
+	unsigned int freq;
+
+	regmap_read(dfs_map, ACPU_DFS_FREQ_REQ, &freq);
+	return freq;
+}
+
+static int hisi_acpu_set_freq(unsigned int freq)
+{
+	/* set the frequency in sram */
+	regmap_write(dfs_map, ACPU_DFS_FREQ_REQ, freq);
+
+	/* send request to power controller */
+	regmap_write(mc_map, MC_COM_CPU_RAW_INT_OFFSET(MC_CORE_ACPU),
+		     (1 << MC_COM_INT_ACPU_DFS));
+	return 0;
+}
+
+static int hisi_acpu_round_freq(unsigned int freq)
+{
+	unsigned int limit_flag, limit_freq = UINT_MAX;
+	unsigned int max_freq;
+
+	/* check the constrainted frequency */
+	regmap_read(dfs_map, ACPU_DFS_FLAG, &limit_flag);
+	if (limit_flag == ACPU_DFS_LOCK_FLAG)
+		regmap_read(dfs_map, ACPU_DFS_FREQ_LMT, &limit_freq);
+
+	/* check the supported maximum frequency */
+	regmap_read(dfs_map, ACPU_DFS_FREQ_MAX, &max_freq);
+
+	/* calculate the real maximum frequency */
+	max_freq = min(max_freq, limit_freq);
+
+	if (WARN_ON(freq > max_freq))
+		freq = max_freq;
+
+	return freq;
+}
+
+static unsigned long hisi_stub_clk_recalc_rate(struct clk_hw *hw,
+		unsigned long parent_rate)
+{
+	u32 rate = 0;
+	struct hisi_stub_clk *stub_clk = to_stub_clk(hw);
+	unsigned long flags;
+
+	spin_lock_irqsave(stub_clk->lock, flags);
+
+	switch (stub_clk->id) {
+	case HISI_STUB_ACPU0:
+		rate = hisi_acpu_get_freq();
+
+		/* convert from KHz to Hz */
+		rate *= 1000;
+		break;
+
+	default:
+		pr_err("%s: un-supported clock id %d\n", __func__,
+			stub_clk->id);
+		break;
+	}
+
+	spin_unlock_irqrestore(stub_clk->lock, flags);
+	return rate;
+}
+
+static int hisi_stub_clk_set_rate(struct clk_hw *hw, unsigned long rate,
+                    unsigned long parent_rate)
+{
+	struct hisi_stub_clk *stub_clk = to_stub_clk(hw);
+	unsigned long flags;
+	unsigned long new_rate = rate / 1000;  /* KHz */
+	int ret = 0;
+
+	spin_lock_irqsave(stub_clk->lock, flags);
+
+	switch (stub_clk->id) {
+	case HISI_STUB_ACPU0:
+		ret = hisi_acpu_set_freq(new_rate);
+		if (ret < 0) {
+			spin_unlock_irqrestore(stub_clk->lock, flags);
+			return ret;
+		}
+
+		break;
+
+	default:
+		pr_err("%s: un-supported clock id %d\n", __func__,
+			stub_clk->id);
+		break;
+	}
+
+	stub_clk->rate = new_rate;
+	spin_unlock_irqrestore(stub_clk->lock, flags);
+
+	pr_debug("%s: set rate=%ldKhz\n", __func__, new_rate);
+	return ret;
+}
+
+static long hisi_stub_clk_round_rate(struct clk_hw *hw, unsigned long rate,
+		unsigned long *parent_rate)
+{
+	struct hisi_stub_clk *stub_clk = to_stub_clk(hw);
+	unsigned long flags;
+	unsigned long new_rate = rate;
+
+	spin_lock_irqsave(stub_clk->lock, flags);
+
+	switch (stub_clk->id) {
+	case HISI_STUB_ACPU0:
+		new_rate = new_rate / 1000;	/* Hz -> KHz */
+		new_rate = hisi_acpu_round_freq(new_rate);
+		new_rate = new_rate * 1000;	/* KHz -> Hz */
+		break;
+
+	default:
+		pr_err("%s: un-supported clock id %d\n", __func__,
+			stub_clk->id);
+		break;
+	}
+
+	spin_unlock_irqrestore(stub_clk->lock, flags);
+	return new_rate;
+}
+
+static struct clk_ops hisi_stub_clk_ops = {
+	.recalc_rate	= hisi_stub_clk_recalc_rate,
+	.round_rate	= hisi_stub_clk_round_rate,
+	.set_rate	= hisi_stub_clk_set_rate,
+};
+
+static int hisi_stub_clk_init(struct device_node *np)
+{
+	int ret = 0;
+	int max_freq;
+
+	dfs_map = syscon_regmap_lookup_by_phandle(np,
+				"hisilicon,clk-stub-sram");
+	if (IS_ERR(dfs_map)) {
+		ret = PTR_ERR(dfs_map);
+		pr_err("failed to get sram regmap: %d\n", ret);
+		return ret;
+	}
+
+	mc_map = syscon_regmap_lookup_by_phandle(np,
+				"hisilicon,clk-stub-mc");
+	if (IS_ERR(mc_map)) {
+		ret = PTR_ERR(mc_map);
+		pr_err("failed to get multi-core comm regmap: %d\n", ret);
+		return ret;
+	}
+
+	/* initialize buffer to zero */
+	regmap_write(dfs_map, ACPU_DFS_FLAG, 0x0);
+	regmap_write(dfs_map, ACPU_DFS_FREQ_REQ, 0x0);
+	regmap_write(dfs_map, ACPU_DFS_FREQ_LMT, 0x0);
+
+	/* At boot time, set to maximum frequency */
+	regmap_read(dfs_map, ACPU_DFS_FREQ_MAX, &max_freq);
+	hisi_acpu_set_freq(max_freq);
+
+	return ret;
+}
+
+static struct clk *_register_stub_clk(struct device *dev, unsigned int id,
+	const char *name, const char *parent_name, unsigned long flags,
+	spinlock_t *lock)
+{
+	struct hisi_stub_clk *stub_clk;
+	struct clk *clk;
+	struct clk_init_data init;
+
+	if (!lock) {
+		pr_err("%s: invalid spinlock pointer\n", __func__);
+		return ERR_PTR(-EINVAL);
+	}
+
+	stub_clk = kzalloc(sizeof(*stub_clk), GFP_KERNEL);
+	if (!stub_clk) {
+		pr_err("%s: fail to alloc stub clk!\n", __func__);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	init.name = name;
+	init.ops = &hisi_stub_clk_ops;
+	init.parent_names = parent_name ? &parent_name : NULL;
+	init.num_parents = parent_name ? 1 : 0;
+	init.flags = flags;
+
+	stub_clk->hw.init = &init;
+	stub_clk->id = id;
+	stub_clk->lock = lock;
+
+	clk = clk_register(dev, &stub_clk->hw);
+	if (IS_ERR(clk)) {
+		pr_err("%s: fail to register stub clk %s!\n", __func__, name);
+		kfree(stub_clk);
+	}
+
+	return clk;
+}
+
+struct clk *hisi_register_stub_clk(struct device_node *np,
+		unsigned int id, const char *name, const char *parent_name,
+		unsigned long flags, spinlock_t *lock)
+{
+	int ret;
+	struct clk *clk;
+
+	pr_debug("[%s]: clk name = %s...\n", __func__, name);
+
+	if (!initialized_stub_clk) {
+		ret = hisi_stub_clk_init(np);
+		if (ret)
+			return ERR_PTR(-EINVAL);
+
+		initialized_stub_clk = 1;
+	}
+
+	clk = _register_stub_clk(NULL, id, name, parent_name, flags, lock);
+	return clk;
+}
diff --git a/drivers/clk/hisilicon/clk.h b/drivers/clk/hisilicon/clk.h
index 624f608..e99184a 100644
--- a/drivers/clk/hisilicon/clk.h
+++ b/drivers/clk/hisilicon/clk.h
@@ -94,6 +94,9 @@ struct clk *hisi_register_clkgate_sep(struct device *, const char *,
 				const char *, unsigned long,
 				void __iomem *, u8,
 				u8, spinlock_t *);
+struct clk *hisi_register_stub_clk(struct device_node *np,
+	unsigned int id, const char *name, const char *parent_name,
+	unsigned long flags, spinlock_t *lock);
 
 struct hisi_clock_data __init *hisi_clk_init(struct device_node *, int);
 struct hisi_clock_data __init *hisi_clk_alloc_data(struct device_node *np,
diff --git a/include/dt-bindings/clock/hisi,stub-clock.h b/include/dt-bindings/clock/hisi,stub-clock.h
new file mode 100644
index 0000000..637d7f5
--- /dev/null
+++ b/include/dt-bindings/clock/hisi,stub-clock.h
@@ -0,0 +1,26 @@
+/*
+ * This header provides constants for Hisilicon stub clock driver.
+ *
+ * Copyright (c) 2015 Hisilicon Limited.
+ * Copyright (c) 2015 Linaro Limited.
+ *
+ * Author: Leo Yan <leo.yan-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _DT_BINDINGS_HISI_STUB_CLOCK_H
+#define _DT_BINDINGS_HISI_STUB_CLOCK_H
+
+/* Stub Clocks */
+#define HISI_STUB_ACPU0		0
+#define HISI_STUB_ACPU1		1
+#define HISI_STUB_GPU		2
+#define HISI_STUB_DDR_MIN	3
+#define HISI_STUB_DDR_MAX	4
+#define HISI_STUB_DDR		5
+#define HISI_STUB_NR_CLKS	6
+
+#endif /* _DT_BINDINGS_HISI_STUB_CLOCK_H */
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html