This patch adds cpufreq driver for Loongson1B which
is capable of changing the CPU frequency dynamically.
Signed-off-by: Kelvin Cheung <keguang.zhang@xxxxxxxxx>
---
drivers/cpufreq/Kconfig | 10 ++
drivers/cpufreq/Makefile | 1 +
drivers/cpufreq/ls1x-cpufreq.c | 229 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 240 insertions(+)
create mode 100644 drivers/cpufreq/ls1x-cpufreq.c
diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index ffe350f..99464d7 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -250,6 +250,16 @@ config LOONGSON2_CPUFREQ
If in doubt, say N.
+config LOONGSON1_CPUFREQ
+ tristate "Loongson1 CPUFreq Driver"
+ help
+ This option adds a CPUFreq driver for loongson1 processors which
+ support software configurable cpu frequency.
+
+ For details, take a look at <file:Documentation/cpu-freq/>.
+
+ If in doubt, say N.
+
endmenu
menu "PowerPC CPU frequency scaling drivers"
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index db6d9a2..aca7bd3 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -98,6 +98,7 @@ obj-$(CONFIG_CRIS_MACH_ARTPEC3) += cris-artpec3-cpufreq.o
obj-$(CONFIG_ETRAXFS) += cris-etraxfs-cpufreq.o
obj-$(CONFIG_IA64_ACPI_CPUFREQ) += ia64-acpi-cpufreq.o
obj-$(CONFIG_LOONGSON2_CPUFREQ) += loongson2_cpufreq.o
+obj-$(CONFIG_LOONGSON1_CPUFREQ) += ls1x-cpufreq.o
obj-$(CONFIG_SH_CPU_FREQ) += sh-cpufreq.o
obj-$(CONFIG_SPARC_US2E_CPUFREQ) += sparc-us2e-cpufreq.o
obj-$(CONFIG_SPARC_US3_CPUFREQ) += sparc-us3-cpufreq.o
diff --git a/drivers/cpufreq/ls1x-cpufreq.c b/drivers/cpufreq/ls1x-cpufreq.c
new file mode 100644
index 0000000..1941c91
--- /dev/null
+++ b/drivers/cpufreq/ls1x-cpufreq.c
@@ -0,0 +1,229 @@
+/*
+ * CPU Frequency Scaling for Loongson 1 SoC
+ *
+ * Copyright (C) 2014 Zhang, Keguang <keguang.zhang@xxxxxxxxx>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include <asm/mach-loongson1/cpufreq.h>
+#include <asm/mach-loongson1/loongson1.h>
+
+static struct {
+ struct device *dev;
+ struct clk *clk; /* CPU clk */
+ struct clk *mux_clk; /* MUX of CPU clk */
+ struct clk *pll_clk; /* PLL clk */
+ struct clk *osc_clk; /* OSC clk */
+ unsigned int max_freq;
+ unsigned int min_freq;
+} ls1x_cpufreq;
+
+static int ls1x_cpufreq_notifier(struct notifier_block *nb,
+ unsigned long val, void *data)
+{
+ if (val == CPUFREQ_POSTCHANGE)
+ current_cpu_data.udelay_val = loops_per_jiffy;
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block ls1x_cpufreq_notifier_block = {
+ .notifier_call = ls1x_cpufreq_notifier
+};
+
+static int ls1x_cpufreq_target(struct cpufreq_policy *policy,
+ unsigned int index)
+{
+ unsigned int old_freq, new_freq;
+
+ old_freq = policy->cur;
+ new_freq = policy->freq_table[index].frequency;
+
+ /*
+ * The procedure of reconfiguring CPU clk is as below.
+ *
+ * - Reparent CPU clk to OSC clk
+ * - Reset CPU clock (very important)
+ * - Reconfigure CPU DIV
+ * - Reparent CPU clk back to CPU DIV clk
+ */
+
+ dev_dbg(ls1x_cpufreq.dev, "%u KHz --> %u KHz\n", old_freq, new_freq);
+ clk_set_parent(policy->clk, ls1x_cpufreq.osc_clk);
+ __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) | RST_CPU_EN | RST_CPU,
+ LS1X_CLK_PLL_DIV);
+ __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) & ~(RST_CPU_EN | RST_CPU),
+ LS1X_CLK_PLL_DIV);
+ clk_set_rate(ls1x_cpufreq.mux_clk, new_freq * 1000);
+ clk_set_parent(policy->clk, ls1x_cpufreq.mux_clk);
+
+ return 0;
+}
+
+static int ls1x_cpufreq_init(struct cpufreq_policy *policy)
+{
+ struct cpufreq_frequency_table *freq_tbl;
+ unsigned int pll_freq, freq;
+ int steps, i, ret;
+
+ pll_freq = clk_get_rate(ls1x_cpufreq.pll_clk) / 1000;
+
+ steps = 1 << DIV_CPU_WIDTH;
+ freq_tbl = kzalloc(sizeof(*freq_tbl) * steps, GFP_KERNEL);
+ if (!freq_tbl) {
+ dev_err(ls1x_cpufreq.dev,
+ "failed to alloc cpufreq_frequency_table\n");
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ for (i = 0; i < (steps - 1); i++) {
+ freq = pll_freq / (i + 1);
+ if ((freq < ls1x_cpufreq.min_freq) ||
+ (freq > ls1x_cpufreq.max_freq))
+ freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID;
+ else
+ freq_tbl[i].frequency = freq;
+ dev_dbg(ls1x_cpufreq.dev,
+ "cpufreq table: index %d: frequency %d\n", i,
+ freq_tbl[i].frequency);
+ }
+ freq_tbl[i].frequency = CPUFREQ_TABLE_END;
+
+ policy->clk = ls1x_cpufreq.clk;
+ ret = cpufreq_generic_init(policy, freq_tbl, 0);
+ if (ret)
+ kfree(freq_tbl);
+out:
+ return ret;
+}
+
+static int ls1x_cpufreq_exit(struct cpufreq_policy *policy)
+{
+ kfree(policy->freq_table);
+ return 0;
+}
+
+static struct cpufreq_driver ls1x_cpufreq_driver = {
+ .name = "cpufreq-ls1x",
+ .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+ .verify = cpufreq_generic_frequency_table_verify,
+ .target_index = ls1x_cpufreq_target,
+ .get = cpufreq_generic_get,
+ .init = ls1x_cpufreq_init,
+ .exit = ls1x_cpufreq_exit,
+ .attr = cpufreq_generic_attr,
+};
+
+static int ls1x_cpufreq_remove(struct platform_device *pdev)
+{
+ cpufreq_unregister_notifier(&ls1x_cpufreq_notifier_block,
+ CPUFREQ_TRANSITION_NOTIFIER);
+ cpufreq_unregister_driver(&ls1x_cpufreq_driver);
+ devm_clk_put(&pdev->dev, ls1x_cpufreq.osc_clk);
+ devm_clk_put(&pdev->dev, ls1x_cpufreq.clk);
+
+ return 0;
+}
+
+static int ls1x_cpufreq_probe(struct platform_device *pdev)
+{
+ struct plat_ls1x_cpufreq *pdata = pdev->dev.platform_data;
+ struct clk *clk;
+ int ret;
+
+ if (!pdata || !pdata->clk_name || !pdata->osc_clk_name)
+ return -EINVAL;
+
+ ls1x_cpufreq.dev = &pdev->dev;
+
+ clk = devm_clk_get(&pdev->dev, pdata->clk_name);
+ if (IS_ERR(clk)) {
+ dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n",
+ pdata->clk_name);
+ ret = PTR_ERR(clk);
+ goto out;
+ }
+ ls1x_cpufreq.clk = clk;
+
+ clk = clk_get_parent(clk);
+ if (IS_ERR(clk)) {
+ dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n",
+ __clk_get_name(ls1x_cpufreq.clk));
+ ret = PTR_ERR(clk);
+ goto err_mux;
+ }
+ ls1x_cpufreq.mux_clk = clk;
+
+ clk = clk_get_parent(clk);
+ if (IS_ERR(clk)) {
+ dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n",
+ __clk_get_name(ls1x_cpufreq.mux_clk));
+ ret = PTR_ERR(clk);
+ goto err_mux;
+ }
+ ls1x_cpufreq.pll_clk = clk;
+
+ clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name);
+ if (IS_ERR(clk)) {
+ dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n",
+ pdata->osc_clk_name);
+ ret = PTR_ERR(clk);
+ goto err_mux;
+ }
+ ls1x_cpufreq.osc_clk = clk;
+
+ ls1x_cpufreq.max_freq = pdata->max_freq;
+ ls1x_cpufreq.min_freq = pdata->min_freq;
+
+ ret = cpufreq_register_driver(&ls1x_cpufreq_driver);
+ if (ret) {
+ dev_err(ls1x_cpufreq.dev,
+ "failed to register cpufreq driver: %d\n", ret);
+ goto err_driver;
+ }
+
+ ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block,
+ CPUFREQ_TRANSITION_NOTIFIER);
+
+ if (!ret)
+ goto out;
+
+ dev_err(ls1x_cpufreq.dev, "failed to register cpufreq notifier: %d\n",
+ ret);
+
+ cpufreq_unregister_driver(&ls1x_cpufreq_driver);
+err_driver:
+ devm_clk_put(&pdev->dev, ls1x_cpufreq.osc_clk);
+err_mux:
+ devm_clk_put(&pdev->dev, ls1x_cpufreq.clk);
+out:
+ return ret;
+}
+
+static struct platform_driver ls1x_cpufreq_platdrv = {
+ .driver = {
+ .name = "ls1x-cpufreq",
+ .owner = THIS_MODULE,
+ },
+ .probe = ls1x_cpufreq_probe,
+ .remove = ls1x_cpufreq_remove,
+};
+
+module_platform_driver(ls1x_cpufreq_platdrv);
+
+MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@xxxxxxxxx>");
+MODULE_DESCRIPTION("Loongson 1 CPUFreq driver");
+MODULE_LICENSE("GPL");
--
1.9.1
