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authorAndrew Lunn <andrew@lunn.ch>2013-02-05 22:52:51 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-02-09 12:56:08 +0100
commit2a4bd9f0db24ba14c8b38777d77add2682233c79 (patch)
treedf5c84538f118e63ff93e13456702086e58708bb /drivers/cpufreq/kirkwood-cpufreq.c
parent93f0822dff5dae2f0a2645f16300c14af41ca777 (diff)
downloadleg-kernel-2a4bd9f0db24ba14c8b38777d77add2682233c79.tar.gz
cpufreq: kirkwood: Add a cpufreq driver for Marvell Kirkwood SoCs
The Marvell Kirkwood SoCs have simple cpufreq support in hardware. The CPU can either use the a high speed cpu clock, or the slower DDR clock. Add a driver to swap between these two clock sources. Signed-off-by: Andrew Lunn <andrew@lunn.ch> Acked-by: Jason Cooper <jason@lakedaemon.net> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/kirkwood-cpufreq.c')
-rw-r--r--drivers/cpufreq/kirkwood-cpufreq.c259
1 files changed, 259 insertions, 0 deletions
diff --git a/drivers/cpufreq/kirkwood-cpufreq.c b/drivers/cpufreq/kirkwood-cpufreq.c
new file mode 100644
index 000000000000..0e83e3c24f5b
--- /dev/null
+++ b/drivers/cpufreq/kirkwood-cpufreq.c
@@ -0,0 +1,259 @@
+/*
+ * kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
+ *
+ * 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/clk-provider.h>
+#include <linux/cpufreq.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <asm/proc-fns.h>
+
+#define CPU_SW_INT_BLK BIT(28)
+
+static struct priv
+{
+ struct clk *cpu_clk;
+ struct clk *ddr_clk;
+ struct clk *powersave_clk;
+ struct device *dev;
+ void __iomem *base;
+} priv;
+
+#define STATE_CPU_FREQ 0x01
+#define STATE_DDR_FREQ 0x02
+
+/*
+ * Kirkwood can swap the clock to the CPU between two clocks:
+ *
+ * - cpu clk
+ * - ddr clk
+ *
+ * The frequencies are set at runtime before registering this *
+ * table.
+ */
+static struct cpufreq_frequency_table kirkwood_freq_table[] = {
+ {STATE_CPU_FREQ, 0}, /* CPU uses cpuclk */
+ {STATE_DDR_FREQ, 0}, /* CPU uses ddrclk */
+ {0, CPUFREQ_TABLE_END},
+};
+
+static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
+{
+ if (__clk_is_enabled(priv.powersave_clk))
+ return kirkwood_freq_table[1].frequency;
+ return kirkwood_freq_table[0].frequency;
+}
+
+static void kirkwood_cpufreq_set_cpu_state(unsigned int index)
+{
+ struct cpufreq_freqs freqs;
+ unsigned int state = kirkwood_freq_table[index].index;
+ unsigned long reg;
+
+ freqs.old = kirkwood_cpufreq_get_cpu_frequency(0);
+ freqs.new = kirkwood_freq_table[index].frequency;
+ freqs.cpu = 0; /* Kirkwood is UP */
+
+ cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+ dev_dbg(priv.dev, "Attempting to set frequency to %i KHz\n",
+ kirkwood_freq_table[index].frequency);
+ dev_dbg(priv.dev, "old frequency was %i KHz\n",
+ kirkwood_cpufreq_get_cpu_frequency(0));
+
+ if (freqs.old != freqs.new) {
+ local_irq_disable();
+
+ /* Disable interrupts to the CPU */
+ reg = readl_relaxed(priv.base);
+ reg |= CPU_SW_INT_BLK;
+ writel_relaxed(reg, priv.base);
+
+ switch (state) {
+ case STATE_CPU_FREQ:
+ clk_disable(priv.powersave_clk);
+ break;
+ case STATE_DDR_FREQ:
+ clk_enable(priv.powersave_clk);
+ break;
+ }
+
+ /* Wait-for-Interrupt, while the hardware changes frequency */
+ cpu_do_idle();
+
+ /* Enable interrupts to the CPU */
+ reg = readl_relaxed(priv.base);
+ reg &= ~CPU_SW_INT_BLK;
+ writel_relaxed(reg, priv.base);
+
+ local_irq_enable();
+ }
+ cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+};
+
+static int kirkwood_cpufreq_verify(struct cpufreq_policy *policy)
+{
+ return cpufreq_frequency_table_verify(policy, kirkwood_freq_table);
+}
+
+static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
+ unsigned int target_freq,
+ unsigned int relation)
+{
+ unsigned int index = 0;
+
+ if (cpufreq_frequency_table_target(policy, kirkwood_freq_table,
+ target_freq, relation, &index))
+ return -EINVAL;
+
+ kirkwood_cpufreq_set_cpu_state(index);
+
+ return 0;
+}
+
+/* Module init and exit code */
+static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
+{
+ int result;
+
+ /* cpuinfo and default policy values */
+ policy->cpuinfo.transition_latency = 5000; /* 5uS */
+ policy->cur = kirkwood_cpufreq_get_cpu_frequency(0);
+
+ result = cpufreq_frequency_table_cpuinfo(policy, kirkwood_freq_table);
+ if (result)
+ return result;
+
+ cpufreq_frequency_table_get_attr(kirkwood_freq_table, policy->cpu);
+
+ return 0;
+}
+
+static int kirkwood_cpufreq_cpu_exit(struct cpufreq_policy *policy)
+{
+ cpufreq_frequency_table_put_attr(policy->cpu);
+ return 0;
+}
+
+static struct freq_attr *kirkwood_cpufreq_attr[] = {
+ &cpufreq_freq_attr_scaling_available_freqs,
+ NULL,
+};
+
+static struct cpufreq_driver kirkwood_cpufreq_driver = {
+ .get = kirkwood_cpufreq_get_cpu_frequency,
+ .verify = kirkwood_cpufreq_verify,
+ .target = kirkwood_cpufreq_target,
+ .init = kirkwood_cpufreq_cpu_init,
+ .exit = kirkwood_cpufreq_cpu_exit,
+ .name = "kirkwood-cpufreq",
+ .owner = THIS_MODULE,
+ .attr = kirkwood_cpufreq_attr,
+};
+
+static int kirkwood_cpufreq_probe(struct platform_device *pdev)
+{
+ struct device_node *np;
+ struct resource *res;
+ int err;
+
+ priv.dev = &pdev->dev;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res) {
+ dev_err(&pdev->dev, "Cannot get memory resource\n");
+ return -ENODEV;
+ }
+ priv.base = devm_request_and_ioremap(&pdev->dev, res);
+ if (!priv.base) {
+ dev_err(&pdev->dev, "Cannot ioremap\n");
+ return -EADDRNOTAVAIL;
+ }
+
+ np = of_find_node_by_path("/cpus/cpu@0");
+ if (!np)
+ return -ENODEV;
+
+ priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
+ if (IS_ERR(priv.cpu_clk)) {
+ dev_err(priv.dev, "Unable to get cpuclk");
+ return PTR_ERR(priv.cpu_clk);
+ }
+
+ clk_prepare_enable(priv.cpu_clk);
+ kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
+
+ priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
+ if (IS_ERR(priv.ddr_clk)) {
+ dev_err(priv.dev, "Unable to get ddrclk");
+ err = PTR_ERR(priv.ddr_clk);
+ goto out_cpu;
+ }
+
+ clk_prepare_enable(priv.ddr_clk);
+ kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
+
+ priv.powersave_clk = of_clk_get_by_name(np, "powersave");
+ if (IS_ERR(priv.powersave_clk)) {
+ dev_err(priv.dev, "Unable to get powersave");
+ err = PTR_ERR(priv.powersave_clk);
+ goto out_ddr;
+ }
+ clk_prepare(priv.powersave_clk);
+
+ of_node_put(np);
+ np = NULL;
+
+ err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
+ if (!err)
+ return 0;
+
+ dev_err(priv.dev, "Failed to register cpufreq driver");
+
+ clk_disable_unprepare(priv.powersave_clk);
+out_ddr:
+ clk_disable_unprepare(priv.ddr_clk);
+out_cpu:
+ clk_disable_unprepare(priv.cpu_clk);
+ of_node_put(np);
+
+ return err;
+}
+
+static int kirkwood_cpufreq_remove(struct platform_device *pdev)
+{
+ cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
+
+ clk_disable_unprepare(priv.powersave_clk);
+ clk_disable_unprepare(priv.ddr_clk);
+ clk_disable_unprepare(priv.cpu_clk);
+
+ return 0;
+}
+
+static struct platform_driver kirkwood_cpufreq_platform_driver = {
+ .probe = kirkwood_cpufreq_probe,
+ .remove = kirkwood_cpufreq_remove,
+ .driver = {
+ .name = "kirkwood-cpufreq",
+ .owner = THIS_MODULE,
+ },
+};
+
+module_platform_driver(kirkwood_cpufreq_platform_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
+MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
+MODULE_ALIAS("platform:kirkwood-cpufreq");