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Diffstat (limited to 'kernel/drivers/cpufreq/kirkwood-cpufreq.c')
-rw-r--r--kernel/drivers/cpufreq/kirkwood-cpufreq.c194
1 files changed, 194 insertions, 0 deletions
diff --git a/kernel/drivers/cpufreq/kirkwood-cpufreq.c b/kernel/drivers/cpufreq/kirkwood-cpufreq.c
new file mode 100644
index 000000000..be42f103d
--- /dev/null
+++ b/kernel/drivers/cpufreq/kirkwood-cpufreq.c
@@ -0,0 +1,194 @@
+/*
+ * 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/cpufreq.h>
+#include <linux/of_device.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[] = {
+ {0, STATE_CPU_FREQ, 0}, /* CPU uses cpuclk */
+ {0, STATE_DDR_FREQ, 0}, /* CPU uses ddrclk */
+ {0, 0, CPUFREQ_TABLE_END},
+};
+
+static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
+{
+ return clk_get_rate(priv.powersave_clk) / 1000;
+}
+
+static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
+ unsigned int index)
+{
+ unsigned int state = kirkwood_freq_table[index].driver_data;
+ unsigned long reg;
+
+ 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_set_parent(priv.powersave_clk, priv.cpu_clk);
+ break;
+ case STATE_DDR_FREQ:
+ clk_set_parent(priv.powersave_clk, priv.ddr_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();
+
+ return 0;
+}
+
+/* Module init and exit code */
+static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
+{
+ return cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
+}
+
+static struct cpufreq_driver kirkwood_cpufreq_driver = {
+ .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+ .get = kirkwood_cpufreq_get_cpu_frequency,
+ .verify = cpufreq_generic_frequency_table_verify,
+ .target_index = kirkwood_cpufreq_target,
+ .init = kirkwood_cpufreq_cpu_init,
+ .name = "kirkwood-cpufreq",
+ .attr = cpufreq_generic_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);
+ priv.base = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(priv.base))
+ return PTR_ERR(priv.base);
+
+ np = of_cpu_device_node_get(0);
+ if (!np) {
+ dev_err(&pdev->dev, "failed to get cpu device node\n");
+ 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_enable(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",
+ },
+};
+
+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");