Re: [PATCH 6/6] cpufreq: Loongson1: Add cpufreq driver for Loongson1B

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On 10 October 2014 09:13, Kelvin Cheung <keguang.zhang@xxxxxxxxx> wrote:

Why should we apply this patch and what is it all about ?

That's what this field is used for, please don't leave it empty.

> Signed-off-by: Kelvin Cheung <keguang.zhang@xxxxxxxxx>
> ---
>  drivers/cpufreq/Kconfig        |  10 ++
>  drivers/cpufreq/Makefile       |   1 +
>  drivers/cpufreq/ls1x-cpufreq.c | 217 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 228 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

Why don't name it like loongson1 to maintain consistency ?

>  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..3d9a410
> --- /dev/null
> +++ b/drivers/cpufreq/ls1x-cpufreq.c
> @@ -0,0 +1,217 @@
> +/*
> + * 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 <cpufreq.h>
> +#include <loongson1.h>

Okay, it looks like I have forgotten some of the C basics :)
But wouldn't the above two lines search for this file in <include/*>, unless
you have compiled it with something like -I include/linux ??
And even then I don't think loongson1.h is present there ..

What am I missing ?

> +
> +static struct {
> +       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;
> +       struct cpufreq_frequency_table *freq_tbl;
> +} 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;
> +}

Why don't you do this at a single place in mips core instead of every
mips cpufreq driver ?

> +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)
> +{
> +       struct device *dev = get_cpu_device(policy->cpu);

Why don't you just save this pointer initially ? And actually
instead of this you should use pdev->dev for all this prints.
This 'dev' is for CPU0 not for driver.

> +       unsigned int old_freq, new_freq;
> +
> +       old_freq = policy->cur;
> +       new_freq = ls1x_cpufreq.freq_tbl[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(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 device *dev = get_cpu_device(policy->cpu);
> +       struct cpufreq_frequency_table *freq_tbl;
> +       unsigned int pll_freq, freq;
> +       int steps, i;
> +
> +       pll_freq = clk_get_rate(ls1x_cpufreq.pll_clk) / 1000;
> +
> +       steps = 1 << DIV_CPU_WIDTH;
> +       freq_tbl = kzalloc(sizeof(*freq_tbl) * steps, GFP_KERNEL);

You never free it, right ? Even on module-removal. Also, why don't allocate
it once at probe time only ?

> +       if (!freq_tbl) {
> +               dev_err(dev, "failed to alloc cpufreq_frequency_table\n");
> +               return -ENOMEM;
> +       }
> +
> +       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(dev, "cpufreq table: index %d: frequency %d\n", i,
> +                       freq_tbl[i].frequency);
> +       }
> +       freq_tbl[i].frequency = CPUFREQ_TABLE_END;
> +       ls1x_cpufreq.freq_tbl = freq_tbl;
> +
> +       policy->clk = ls1x_cpufreq.clk;
> +       return cpufreq_generic_init(policy, ls1x_cpufreq.freq_tbl, 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,
> +       .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;
> +

Try this code here:

pdata = NULL;

> +       if (!pdata && !pdata->clk_name && !pdata->osc_clk_name) {

And tell me what happens here then. :)

> +               ret = -EINVAL;
> +               goto out;
> +       }
> +
> +       clk = clk_get(NULL, pdata->clk_name);

To make life simple, why not use devm_clk_get() here and at other places ?

> +       if (IS_ERR(clk)) {
> +               dev_err(&pdev->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(&pdev->dev, "unable to get parent of %s clock\n",
> +                       __clk_get_name(ls1x_cpufreq.clk));

@Mike: Is it fine to include clk-provider for this?

> +               ret = PTR_ERR(clk);
> +               goto err_mux;
> +       }
> +       ls1x_cpufreq.mux_clk = clk;
> +
> +       clk = clk_get_parent(clk);
> +       if (IS_ERR(clk)) {
> +               dev_err(&pdev->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(&pdev->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(&pdev->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(&pdev->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 <keguang.zhang@xxxxxxxxx>");
> +MODULE_DESCRIPTION("Loongson 1 CPUFreq driver");
> +MODULE_LICENSE("GPL");
> --
> 1.9.1
>





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