[PATCH V2 7/7] arm/imx6q: add cpufreq support

[Rob Lee]

On 13 December 2011 04:38, Richard Zhao <richard.zhao at freescale.com> wrote:
> On Tue, Dec 13, 2011 at 11:23:15AM +0100, Sascha Hauer wrote:
>> On Tue, Dec 13, 2011 at 02:25:30PM +0800, Richard Zhao wrote:
>> > use cpu0 node property clock-frequency to check max frequency.
>> >
>> > Signed-off-by: Richard Zhao <richard.zhao at linaro.org>
>> > ---
>> >  arch/arm/mach-imx/Kconfig        |    1 +
>> >  arch/arm/mach-imx/Makefile       |    2 +-
>> >  arch/arm/mach-imx/cpu_op-imx6q.c |   69 ++++++++++++++++++++++++++++++++++++++
>> >  3 files changed, 71 insertions(+), 1 deletions(-)
>> >  create mode 100644 arch/arm/mach-imx/cpu_op-imx6q.c
>> >
>> > diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig
>> > index fbd414b..21e472f 100644
>> > --- a/arch/arm/mach-imx/Kconfig
>> > +++ b/arch/arm/mach-imx/Kconfig
>> > @@ -834,6 +834,7 @@ comment "i.MX6 family:"
>> >
>> >  config SOC_IMX6Q
>> >     bool "i.MX6 Quad support"
>> > +   select ARCH_HAS_CPUFREQ
>> >     select ARM_GIC
>> >     select CACHE_L2X0
>> >     select CPU_V7
>> > diff --git a/arch/arm/mach-imx/Makefile b/arch/arm/mach-imx/Makefile
>> > index 9cf630a..2dfe4a7 100644
>> > --- a/arch/arm/mach-imx/Makefile
>> > +++ b/arch/arm/mach-imx/Makefile
>> > @@ -72,7 +72,7 @@ AFLAGS_head-v7.o :=-Wa,-march=armv7-a
>> >  obj-$(CONFIG_SMP) += platsmp.o
>> >  obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
>> >  obj-$(CONFIG_LOCAL_TIMERS) += localtimer.o
>> > -obj-$(CONFIG_SOC_IMX6Q) += clock-imx6q.o mach-imx6q.o pm-imx6q.o
>> > +obj-$(CONFIG_SOC_IMX6Q) += clock-imx6q.o mach-imx6q.o pm-imx6q.o cpu_op-imx6q.o
>> >
>> >  # i.MX5 based machines
>> >  obj-$(CONFIG_MACH_MX51_BABBAGE) += mach-mx51_babbage.o
>> > diff --git a/arch/arm/mach-imx/cpu_op-imx6q.c b/arch/arm/mach-imx/cpu_op-imx6q.c
>> > new file mode 100644
>> > index 0000000..d24e081
>> > --- /dev/null
>> > +++ b/arch/arm/mach-imx/cpu_op-imx6q.c
>> > @@ -0,0 +1,69 @@
>> > +/*
>> > + * Copyright (C) 2011 Freescale Semiconductor, Inc. All Rights Reserved.
>> > + */
>> > +
>> > +/*
>> > + * The code contained herein is licensed under the GNU General Public
>> > + * License. You may obtain a copy of the GNU General Public License
>> > + * Version 2 or later at the following locations:
>> > + *
>> > + * http://www.opensource.org/licenses/gpl-license.html
>> > + * http://www.gnu.org/copyleft/gpl.html
>> > + */
>> > +
>> > +#include <linux/types.h>
>> > +#include <linux/kernel.h>
>> > +#include <linux/string.h>
>> > +#include <linux/of.h>
>> > +#include <mach/hardware.h>
>> > +
>> > +static int arm_max_freq_idx;
>>
>> This is only used in mx6q_get_cpu_op()
> I'll move to local var
>>
>> Also shouldn't this be initialized with 1? From what you
>> said 800MHz is safe for all boards whereas 1GHz is not.
> I'll fix it in next version.
>

Richard, I communicated with Hui Liu a couple of weeks ago about the
possibility of adding a "max_freq" kernel parameter to the i.MX6q
community u-boot, similiar to what has been done for the BSP u-boot.
If he is or has done this, it may be better to read and use this
kernel parameter from u-boot so that the same kernel can be used
between boards with and without the fix.  I'm not that familiar with
device tree yet but perhaps it provides another way to handle this.
Also keep in

> Thanks
> Richard
>>
>> Sascha
>>
>> > +
>> > +/* operating point(op): 0 - 1GHz; 1 - 800MHz, 3 - 400MHz, 4  - 160MHz */
>> > +static struct cpu_op mx6q_cpu_op[] = {
>> > +   {
>> > +           .cpu_rate = 996000000,
>> > +           .cpu_voltage = 1225000,
>> > +   },
>> > +   {
>> > +           .cpu_rate = 792000000,
>> > +           .cpu_voltage = 1100000,
>> > +   },
>> > +   {
>> > +           .cpu_rate = 396000000,
>> > +           .cpu_voltage = 950000,
>> > +   },
>> > +   {
>> > +           .cpu_rate = 198000000,
>> > +           .cpu_voltage = 850000,
>> > +   },
>> > +};
>> > +
>> > +struct cpu_op *mx6q_get_cpu_op(int *op)
>> > +{
>> > +   struct device_node *cpu0;
>> > +   u32 val;
>> > +   int i;
>> > +
>> > +   cpu0 = of_find_node_by_path("/cpus/cpu at 0");
>> > +   if (cpu0 && !of_property_read_u32(cpu0, "clock-frequency", &val)) {
>> > +           for (i = 0; i < ARRAY_SIZE(mx6q_cpu_op); i++) {
>> > +                   if (val >= mx6q_cpu_op[i].cpu_rate) {
>> > +                           arm_max_freq_idx = i;
>> > +                           break;
>> > +                   }
>> > +           }
>> > +   }
>> > +   if (cpu0)
>> > +           of_node_put(cpu0);
>> > +   *op = ARRAY_SIZE(mx6q_cpu_op) - arm_max_freq_idx;
>> > +   return mx6q_cpu_op + arm_max_freq_idx;
>> > +}
>> > +
>> > +static int __init mx6q_cpu_op_init(void)
>> > +{
>> > +   get_cpu_op = mx6q_get_cpu_op;
>> > +   return 0;
>> > +}
>> > +
>> > +core_initcall(mx6q_cpu_op_init);
>> > --
>> > 1.7.5.4
>> >
>> >
>> >
>>
>> --
>> Pengutronix e.K.                           |                             |
>> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
>> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
>> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
>>
>> _______________________________________________
>> linux-arm-kernel mailing list
>> linux-arm-kernel at lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>>
>