[PATCH 6/6] cpufreq: Loongson1: Add cpufreq driver for Loongson1B (UPDATED)

[Kelvin Cheung]

This patch adds cpufreq driver for Loongson1B which
is capable of changing the CPU frequency dynamically.

Signed-off-by: Kelvin Cheung <***@gmail.com>
---
drivers/cpufreq/Kconfig | 10 ++
drivers/cpufreq/Makefile | 1 +
drivers/cpufreq/ls1x-cpufreq.c | 233 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 244 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..2655960
--- /dev/null
+++ b/drivers/cpufreq/ls1x-cpufreq.c
@@ -0,0 +1,233 @@
+/*
+ * CPU Frequency Scaling for Loongson 1 SoC
+ *
+ * Copyright (C) 2014 Zhang, Keguang <***@gmail.com>
+ *
+ * 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);
+ clk_put(ls1x_cpufreq.osc_clk);
+ clk_put(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)
+ return -EINVAL;
+ if (!pdata->clk_name)
+ return -EINVAL;
+ if (!pdata->osc_clk_name)
+ return -EINVAL;
+
+ ls1x_cpufreq.dev = &pdev->dev;
+
+ clk = clk_get(NULL, 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 = clk_get(NULL, 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:
+ clk_put(ls1x_cpufreq.osc_clk);
+err_mux:
+ clk_put(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 <***@gmail.com>");
+MODULE_DESCRIPTION("Loongson 1 CPUFreq driver");
+MODULE_LICENSE("GPL");

[Viresh Kumar]

This is not how we send updated versions, GIT and other tools will commit
the "(UPDATED)" part while applying. What you were required to do was
something like:

git format-patch A..B --subject-prefix="PATCH V2"

Post by Kelvin Cheung
+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);
+ clk_put(ls1x_cpufreq.osc_clk);
+ clk_put(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)
+ return -EINVAL;
+ if (!pdata->clk_name)
+ return -EINVAL;
+ if (!pdata->osc_clk_name)
+ return -EINVAL;

I didn't wanted you to do this, You could have done this:

if (!pdata || !pdata->clk_name || !pdata->osc_clk_name)
return -EINVAL;

So, just a || instead of && :)

Post by Kelvin Cheung
+
+ ls1x_cpufreq.dev = &pdev->dev;
+
+ clk = clk_get(NULL, pdata->clk_name);

I believe we agreed for devm_clk_get(), isn't it ?

Post by Kelvin Cheung
+ 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 = clk_get(NULL, 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);
+ clk_put(ls1x_cpufreq.osc_clk);
+ clk_put(ls1x_cpufreq.clk);
+ 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_DESCRIPTION("Loongson 1 CPUFreq driver");
+MODULE_LICENSE("GPL");
--
1.9.1

[Viresh Kumar]

On 16 October 2014 15:00, Kelvin Cheung <***@gmail.com> wrote:

Just to let u know, your mails are probably generated in html whereas they
should be in text mode.

Post by Viresh Kumar
This is not how we send updated versions, GIT and other tools will commit
the "(UPDATED)" part while applying. What you were required to do was
git format-patch A..B --subject-prefix="PATCH V2"

I use 'updated' because only one patch in the patch set need to be updated.
If you insist, I will regenerate this patch.

Even in that case you can do what I was saying. No, you don't need to resend
for that reason now. :)

Post by Viresh Kumar

Post by Kelvin Cheung
+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);
+ clk_put(ls1x_cpufreq.osc_clk);
+ clk_put(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)
+ return -EINVAL;
+ if (!pdata->clk_name)
+ return -EINVAL;
+ if (!pdata->osc_clk_name)
+ return -EINVAL;

if (!pdata || !pdata->clk_name || !pdata->osc_clk_name)
return -EINVAL;
So, just a || instead of && :)

Post by Kelvin Cheung
+
+ ls1x_cpufreq.dev = &pdev->dev;
+
+ clk = clk_get(NULL, pdata->clk_name);

I believe we agreed for devm_clk_get(), isn't it ?

In my case I think clk_get() is enough.

Obviously its enough but wouldn't it be better to use a infrastructure
which is somewhat better ?

Moreover, most of cpufreq drivers use clk_get().

So what? Is that a good enough reason for adopting a good change?

[Aaro Koskinen]

Hi,

Post by Kelvin Cheung
This patch adds cpufreq driver for Loongson1B which
is capable of changing the CPU frequency dynamically.

[...]

Post by Kelvin Cheung
obj-$(CONFIG_LOONGSON2_CPUFREQ) += loongson2_cpufreq.o
+obj-$(CONFIG_LOONGSON1_CPUFREQ) += ls1x-cpufreq.o

Why it's called "ls1x-cpufreq" instead of "loongson1_cpufreq"?

A.
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[Viresh Kumar]

Post by Aaro Koskinen
Why it's called "ls1x-cpufreq" instead of "loongson1_cpufreq"?

This is what Kelvin told me when I asked him the same query:

Other drivers of loongson1 are already named *ls1x*, such as
clk-ls1x.c and rtc-ls1x.c.
So I just keep pace with them.
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