[PATCH 1/4] cpufreq: Add a cpufreq driver for Marvell Dove

[andrew@lunn.ch (Andrew Lunn)]

The Marvell Dove SoC can run the CPU at two frequencies. The high
frequencey is from a PLL, while the lower is the same as the DDR
clock. Add a cpufreq driver to swap between these frequences.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
---
Sort header files
Remove unneeded header files
Notify only on change
Use get_cpu_device(0), devm_clk_get()
Use platform_get_resource_byname()
Error check clk_prepare_enable()
Comment the interrupt handler
---
 drivers/cpufreq/Kconfig.arm    |   5 +
 drivers/cpufreq/Makefile       |   1 +
 drivers/cpufreq/dove-cpufreq.c | 279 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 285 insertions(+)
 create mode 100644 drivers/cpufreq/dove-cpufreq.c

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index 701ec95..9560384 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -8,6 +8,11 @@ config ARM_BIG_LITTLE_CPUFREQ
 	help
 	  This enables the Generic CPUfreq driver for ARM big.LITTLE platforms.
 
+config ARM_DOVE_CPUFREQ
+	def_bool ARCH_DOVE && OF
+	help
+	  This adds the CPUFreq driver for Marvell Dove SoCs.
+
 config ARM_DT_BL_CPUFREQ
 	tristate "Generic probing via DT for ARM big LITTLE CPUfreq driver"
 	depends on ARM_BIG_LITTLE_CPUFREQ && OF
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index b7948bb..5956661 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -49,6 +49,7 @@ obj-$(CONFIG_ARM_DT_BL_CPUFREQ)		+= arm_big_little_dt.o
 
 obj-$(CONFIG_ARCH_DAVINCI_DA850)	+= davinci-cpufreq.o
 obj-$(CONFIG_UX500_SOC_DB8500)		+= dbx500-cpufreq.o
+obj-$(CONFIG_ARM_DOVE_CPUFREQ)		+= dove-cpufreq.o
 obj-$(CONFIG_ARM_EXYNOS_CPUFREQ)	+= exynos-cpufreq.o
 obj-$(CONFIG_ARM_EXYNOS4210_CPUFREQ)	+= exynos4210-cpufreq.o
 obj-$(CONFIG_ARM_EXYNOS4X12_CPUFREQ)	+= exynos4x12-cpufreq.o
diff --git a/drivers/cpufreq/dove-cpufreq.c b/drivers/cpufreq/dove-cpufreq.c
new file mode 100644
index 0000000..10f013c
--- /dev/null
+++ b/drivers/cpufreq/dove-cpufreq.c
@@ -0,0 +1,279 @@
+/*
+ *	dove_freq.c: cpufreq driver for the Marvell dove
+ *
+ *	Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch>
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <asm/proc-fns.h>
+
+#define DFS_CR			0x00
+#define  DFS_EN			BIT(0)
+#define  CPU_SLOW_EN		BIT(1)
+#define  L2_RATIO_OFFS		9
+#define  L2_RATIO_MASK		(0x3F << L2_RATIO_OFFS)
+#define DFS_SR			0x04
+#define  CPU_SLOW_MODE_STTS	BIT(1)
+
+/* PMU_CR */
+#define  MASK_FIQ		BIT(28)
+#define  MASK_IRQ		BIT(24)	/* PMU_CR */
+
+/* CPU Clock Divider Control 0 Register */
+#define DPRATIO_OFFS		24
+#define DPRATIO_MASK		(0x3F << DPRATIO_OFFS)
+#define XPRATIO_OFFS		16
+#define XPRATIO_MASK		(0x3F << XPRATIO_OFFS)
+
+static struct priv
+{
+	struct clk *cpu_clk;
+	struct clk *ddr_clk;
+	struct device *dev;
+	unsigned long dpratio;
+	unsigned long xpratio;
+	void __iomem *dfs;
+	void __iomem *pmu_cr;
+	void __iomem *pmu_clk_div;
+} priv;
+
+#define STATE_CPU_FREQ 0x01
+#define STATE_DDR_FREQ 0x02
+
+/*
+ * Dove can swap the clock to the CPU between two clocks:
+ *
+ * - cpu clk
+ * - ddr clk
+ *
+ * The frequencies are set@runtime before registering this
+ * table.
+ */
+static struct cpufreq_frequency_table dove_freq_table[] = {
+	{STATE_CPU_FREQ,	0}, /* CPU uses cpuclk */
+	{STATE_DDR_FREQ,	0}, /* CPU uses ddrclk */
+	{0,			CPUFREQ_TABLE_END},
+};
+
+static unsigned int dove_cpufreq_get_cpu_frequency(unsigned int cpu)
+{
+	unsigned long reg = readl_relaxed(priv.dfs + DFS_SR);
+
+	if (reg & CPU_SLOW_MODE_STTS)
+		return dove_freq_table[1].frequency;
+	return dove_freq_table[0].frequency;
+}
+
+static void dove_cpufreq_set_cpu_state(struct cpufreq_policy *policy,
+				       unsigned int index)
+{
+	struct cpufreq_freqs freqs;
+	unsigned int state = dove_freq_table[index].driver_data;
+	unsigned long reg, cr;
+
+	freqs.old = dove_cpufreq_get_cpu_frequency(0);
+	freqs.new = dove_freq_table[index].frequency;
+
+	if (freqs.old != freqs.new) {
+		cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
+		local_irq_disable();
+
+		/* Mask IRQ and FIQ to CPU */
+		cr = readl(priv.pmu_cr);
+		cr |= MASK_IRQ | MASK_FIQ;
+		writel(cr, priv.pmu_cr);
+
+		/* Set/Clear the CPU_SLOW_EN bit */
+		reg = readl_relaxed(priv.dfs + DFS_CR);
+		reg &= ~L2_RATIO_MASK;
+
+		switch (state) {
+		case STATE_CPU_FREQ:
+			reg |= priv.xpratio;
+			reg &= ~CPU_SLOW_EN;
+			break;
+		case STATE_DDR_FREQ:
+			reg |= (priv.dpratio | CPU_SLOW_EN);
+			break;
+		}
+
+		/* Start the DFS process */
+		reg |= DFS_EN;
+
+		writel(reg, priv.dfs + DFS_CR);
+
+		/* Wait-for-Interrupt, while the hardware changes frequency */
+		cpu_do_idle();
+
+		local_irq_enable();
+		cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
+	}
+}
+
+static int dove_cpufreq_target(struct cpufreq_policy *policy,
+			    unsigned int target_freq,
+			    unsigned int relation)
+{
+	unsigned int index = 0;
+
+	if (cpufreq_frequency_table_target(policy, dove_freq_table,
+				target_freq, relation, &index))
+		return -EINVAL;
+
+	dove_cpufreq_set_cpu_state(policy, index);
+
+	return 0;
+}
+
+static int dove_cpufreq_cpu_init(struct cpufreq_policy *policy)
+{
+	return cpufreq_generic_init(policy, dove_freq_table, 5000);
+}
+
+/*
+ * Handle the interrupt raised when the frequency change is
+ * complete.
+ */
+static irqreturn_t dove_cpufreq_irq(int irq, void *dev)
+{
+	return IRQ_HANDLED;
+}
+
+static struct cpufreq_driver dove_cpufreq_driver = {
+	.get	= dove_cpufreq_get_cpu_frequency,
+	.verify	= cpufreq_generic_frequency_table_verify,
+	.target = dove_cpufreq_target,
+	.init	= dove_cpufreq_cpu_init,
+	.exit	= cpufreq_generic_exit,
+	.name	= "dove-cpufreq",
+	.attr	= cpufreq_generic_attr,
+};
+
+static int dove_cpufreq_probe(struct platform_device *pdev)
+{
+	struct device *cpu_dev;
+	struct resource *res;
+	int err, irq;
+
+	memset(&priv, 0, sizeof(priv));
+	priv.dev = &pdev->dev;
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+					   "cpufreq: DFS");
+	priv.dfs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(priv.dfs))
+		return PTR_ERR(priv.dfs);
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+					   "cpufreq: PMU CR");
+	priv.pmu_cr = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(priv.pmu_cr))
+		return PTR_ERR(priv.pmu_cr);
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
+					   "cpufreq: PMU Clk Div");
+	priv.pmu_clk_div = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(priv.pmu_clk_div))
+		return PTR_ERR(priv.pmu_clk_div);
+
+	cpu_dev = get_cpu_device(0);
+
+	priv.cpu_clk = devm_clk_get(cpu_dev, "cpu_clk");
+	if (IS_ERR(priv.cpu_clk)) {
+		err = PTR_ERR(priv.cpu_clk);
+		goto out;
+	}
+
+	err = clk_prepare_enable(priv.cpu_clk);
+	if (err)
+		goto out;
+
+	dove_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
+
+	priv.ddr_clk = devm_clk_get(cpu_dev, "ddrclk");
+	if (IS_ERR(priv.ddr_clk)) {
+		err = PTR_ERR(priv.ddr_clk);
+		goto out;
+	}
+
+	err = clk_prepare_enable(priv.ddr_clk);
+	if (err)
+		goto out;
+
+	dove_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
+
+	irq = irq_of_parse_and_map(cpu_dev->of_node, 0);
+	if (!irq) {
+		err = -ENXIO;
+		goto out;
+	}
+
+	err = devm_request_irq(&pdev->dev, irq, dove_cpufreq_irq,
+			       0, "dove-cpufreq", NULL);
+	if (err) {
+		dev_err(&pdev->dev, "cannot assign irq %d, %d\n", irq, err);
+		goto out;
+	}
+
+	/* Read the target ratio which should be the DDR ratio */
+	priv.dpratio = readl_relaxed(priv.pmu_clk_div);
+	priv.dpratio = (priv.dpratio & DPRATIO_MASK) >> DPRATIO_OFFS;
+	priv.dpratio = priv.dpratio << L2_RATIO_OFFS;
+
+	/* Save L2 ratio@reset */
+	priv.xpratio = readl(priv.pmu_clk_div);
+	priv.xpratio = (priv.xpratio & XPRATIO_MASK) >> XPRATIO_OFFS;
+	priv.xpratio = priv.xpratio << L2_RATIO_OFFS;
+
+	err = cpufreq_register_driver(&dove_cpufreq_driver);
+	if (!err)
+		return 0;
+
+	dev_err(priv.dev, "Failed to register cpufreq driver");
+
+out:
+	clk_disable_unprepare(priv.ddr_clk);
+	clk_disable_unprepare(priv.cpu_clk);
+
+	return err;
+}
+
+static int dove_cpufreq_remove(struct platform_device *pdev)
+{
+	cpufreq_unregister_driver(&dove_cpufreq_driver);
+
+	clk_disable_unprepare(priv.ddr_clk);
+	clk_disable_unprepare(priv.cpu_clk);
+
+	return 0;
+}
+
+static struct platform_driver dove_cpufreq_platform_driver = {
+	.probe = dove_cpufreq_probe,
+	.remove = dove_cpufreq_remove,
+	.driver = {
+		.name = "dove-cpufreq",
+		.owner = THIS_MODULE,
+	},
+};
+
+module_platform_driver(dove_cpufreq_platform_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
+MODULE_DESCRIPTION("cpufreq driver for Marvell's dove CPU");
+MODULE_ALIAS("platform:dove-cpufreq");
-- 
1.8.4.rc3