Subject: [RFC][PATCH 1/2] ARM: OMAP4: clock: Add device tree support for AUXCLKs

From: [email-masked] (Mike Turquette)
Date: Wed, 10 Apr 2013 01:06:30 -0700

Quoting Nishanth Menon (2013-04-09 13:49:00)
> On 10:43-20130409, Tony Lindgren wrote:
> > * Tony Lindgren <[email-masked]> [130409 09:54]:
> > > * Roger Quadros <[email-masked]> [130409 03:00]:
> > > > On 04/05/2013 06:58 PM, Tony Lindgren wrote:
> > > > > 
> > > > > Can't you just use the clock name there to get it?
> > > > 
> > > > In device tree we don't pass around clock names. You can either get
> > > > a phandle or an index to the clock.
> > > > 
> > > > e.g. Documentation/devicetree/bindings/clock/imx31-clock.txt
> > > 
> > > Yes I understand that. But the driver/clock/omap driver can just
> > > remap the DT device initially so the board specific clock is
> > > found from the clock alias table. Basically initially a passthrough
> > > driver that can be enhanced to parse DT clock bindings and load
> > > data from /lib/firmware.
> > 
> > Actually probably the driver/clock/omap can even do even less
> > initially. There probably even no need to remap clocks there.
> > 
> > As long as the DT clock driver understands that a board specific
> > auxclk is specified in the DT it can just call clk_add_alias() so
> > the driver will get the right auxclk from cclock44xx_data.c.
> > 
> > Then other features can be added later on like to allocate a
> > clock entirely based on the binding etc.
> I did try to have an implementation for cpufreq using clock nodes.
> unfortunately, device tree wont let me have arguments of strings :(
> So, I am unable to do clock = <&clk mpu_dpll>;
> instead, I am forced to do clock = <&clk 249>;
> 

See http://article.gmane.org/gmane.linux.ports.arm.kernel/229034

Regards,
Mike

> Here is an attempt on beagleXM - adds every clock node to the list.
> Tons of un-necessary prints added to give an idea - see log:
> http://pastebin.com/F9A2zSTr
> 
> Would an cleaned up version be good enough as a step #1 of transition?
> 
> From 7d373bdb9e9549c1b6ba1775a8dfd96ebe78abfb Mon Sep 17 00:00:00 2001
> From: Nishanth Menon <[email-masked]>
> Date: Tue, 26 Mar 2013 10:23:27 +0000
> Subject: [PATCH] OMAP: add devicetree support for clock nodes.
> 
> Dummy patch based on Roger's original idea
> 
> Nyet-Signed-off-by: Nishanth Menon <[email-masked]>
> ---
>  arch/arm/boot/dts/omap3.dtsi          |    5 ++
>  arch/arm/boot/dts/omap34xx.dtsi       |    2 +
>  arch/arm/mach-omap2/cclock3xxx_data.c |    3 +-
>  arch/arm/mach-omap2/cclock44xx_data.c |    3 +-
>  arch/arm/mach-omap2/pm.c              |   11 +++-
>  drivers/clk/Kconfig                   |    6 ++
>  drivers/clk/Makefile                  |    2 +
>  drivers/clk/ti.c                      |  100 +++++++++++++++++++++++++++++++++
>  include/linux/clk/ti.h                |   30 ++++++++++
>  9 files changed, 157 insertions(+), 5 deletions(-)
>  create mode 100644 drivers/clk/ti.c
>  create mode 100644 include/linux/clk/ti.h
> 
> diff --git a/arch/arm/boot/dts/omap3.dtsi b/arch/arm/boot/dts/omap3.dtsi
> index 3344f05..a08990d 100644
> --- a/arch/arm/boot/dts/omap3.dtsi
> +++ b/arch/arm/boot/dts/omap3.dtsi
> @@ -73,6 +73,11 @@
>                         ti,hwmods = "counter_32k";
>                 };
>  
> +               clks: clocks {
> +                       compatible = "ti,clock";
> +                       #clock-cells = <1>;
> +               };
> +
>                 intc: interrupt-controller at 48200000 {
>                         compatible = "ti,omap2-intc";
>                         interrupt-controller;
> diff --git a/arch/arm/boot/dts/omap34xx.dtsi b/arch/arm/boot/dts/omap34xx.dtsi
> index 75ed4ae..93c2621 100644
> --- a/arch/arm/boot/dts/omap34xx.dtsi
> +++ b/arch/arm/boot/dts/omap34xx.dtsi
> @@ -23,6 +23,8 @@
>                                 600000  1350000
>                         >;
>                         clock-latency = <300000>; /* From legacy driver */
> +                       clocks = <&clks 249>; /* index to cpufreq_ck */
> +                       clock-names = "cpu";
>                 };
>         };
>  };
> diff --git a/arch/arm/mach-omap2/cclock3xxx_data.c b/arch/arm/mach-omap2/cclock3xxx_data.c
> index 4579c3c..d5d5ef5 100644
> --- a/arch/arm/mach-omap2/cclock3xxx_data.c
> +++ b/arch/arm/mach-omap2/cclock3xxx_data.c
> @@ -22,6 +22,7 @@
>  #include <linux/clk-private.h>
>  #include <linux/list.h>
>  #include <linux/io.h>
> +#include <linux/clk/ti.h>
>  
>  #include "soc.h"
>  #include "iomap.h"
> @@ -3574,7 +3575,7 @@ int __init omap3xxx_clk_init(void)
>         for (c = omap3xxx_clks; c < omap3xxx_clks + ARRAY_SIZE(omap3xxx_clks);
>              c++)
>                 if (c->cpu & cpu_clkflg) {
> -                       clkdev_add(&c->lk);
> +                       ti_clk_node_add(&c->lk);
>                         if (!__clk_init(NULL, c->lk.clk))
>                                 omap2_init_clk_hw_omap_clocks(c->lk.clk);
>                 }
> diff --git a/arch/arm/mach-omap2/cclock44xx_data.c b/arch/arm/mach-omap2/cclock44xx_data.c
> index 0c6834a..338ef64 100644
> --- a/arch/arm/mach-omap2/cclock44xx_data.c
> +++ b/arch/arm/mach-omap2/cclock44xx_data.c
> @@ -27,6 +27,7 @@
>  #include <linux/clk-private.h>
>  #include <linux/clkdev.h>
>  #include <linux/io.h>
> +#include <linux/clk/ti.h>
>  
>  #include "soc.h"
>  #include "iomap.h"
> @@ -1697,7 +1698,7 @@ int __init omap4xxx_clk_init(void)
>         for (c = omap44xx_clks; c < omap44xx_clks + ARRAY_SIZE(omap44xx_clks);
>                                                                         c++) {
>                 if (c->cpu & cpu_clkflg) {
> -                       clkdev_add(&c->lk);
> +                       ti_clk_node_add(&c->lk);
>                         if (!__clk_init(NULL, c->lk.clk))
>                                 omap2_init_clk_hw_omap_clocks(c->lk.clk);
>                 }
> diff --git a/arch/arm/mach-omap2/pm.c b/arch/arm/mach-omap2/pm.c
> index 8d15f9a..6cf95160 100644
> --- a/arch/arm/mach-omap2/pm.c
> +++ b/arch/arm/mach-omap2/pm.c
> @@ -267,7 +267,12 @@ static void __init omap4_init_voltages(void)
>  
>  static inline void omap_init_cpufreq(void)
>  {
> -       struct platform_device_info devinfo = { .name = "omap-cpufreq", };
> +       struct platform_device_info devinfo = { };
> +
> +       if (!of_have_populated_dt())
> +               devinfo.name = "omap-cpufreq";
> +       else
> +               devinfo.name = "cpufreq-cpu0";
>         platform_device_register_full(&devinfo);
>  }
>  
> @@ -301,9 +306,9 @@ int __init omap2_common_pm_late_init(void)
>                 /* Smartreflex device init */
>                 omap_devinit_smartreflex();
>  
> -               /* cpufreq dummy device instantiation */
> -               omap_init_cpufreq();
>         }
> +       /* cpufreq dummy device instantiation */
> +       omap_init_cpufreq();
>  
>  #ifdef CONFIG_SUSPEND
>         suspend_set_ops(&omap_pm_ops);
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index a47e6ee..03c6e48 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -55,6 +55,12 @@ config COMMON_CLK_MAX77686
>         ---help---
>           This driver supports Maxim 77686 crystal oscillator clock. 
>  
> +config COMMON_CLK_TI
> +       tristate "Clock driver for TI SoCs"
> +       depends on ARCH_OMAP && OF
> +       ---help---
> +         Fill me up.. some generic statement ofcourse (lets start with OMAP)
> +
>  config CLK_TWL6040
>         tristate "External McPDM functional clock from twl6040"
>         depends on TWL6040_CORE
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index 300d477..9621815 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -30,6 +30,8 @@ obj-$(CONFIG_ARCH_TEGRA)      += tegra/
>  
>  obj-$(CONFIG_X86)              += x86/
>  
> +obj-$(CONFIG_COMMON_CLK_TI)    += ti.o
> +
>  # Chip specific
>  obj-$(CONFIG_COMMON_CLK_WM831X) += clk-wm831x.o
>  obj-$(CONFIG_COMMON_CLK_MAX77686) += clk-max77686.o
> diff --git a/drivers/clk/ti.c b/drivers/clk/ti.c
> new file mode 100644
> index 0000000..c747381
> --- /dev/null
> +++ b/drivers/clk/ti.c
> @@ -0,0 +1,100 @@
> +/*
> + * TI Clock node provider
> + *
> + * Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com/
> + *     Nishanth Menon
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> + * kind, whether express or implied; without even the implied warranty
> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +#include <linux/kernel.h>
> +#include <linux/list.h>
> +#include <linux/clk-private.h>
> +#include <linux/clkdev.h>
> +#include <linux/io.h>
> +#include <linux/of.h>
> +#include <linux/clk/ti.h>
> +
> +struct ti_clk {
> +       struct clk_lookup *lk;
> +       struct list_head node;
> +};
> +
> +static LIST_HEAD(ti_clk_list);
> +
> +static struct clk *ti_bypass_clk_get_by_name(struct of_phandle_args *clkspec,
> +                                            void *data)
> +{
> +       struct ti_clk *c;
> +#if 0
> +       /* Eww.. IF ONLY phandle arguments could be string */
> +       char clk_name[32]; /* 32 is max size of property name */
> +
> +       char *name = clkspec->args[0];
> +
> +       snprintf(clk_name, 32, "%s_ck", name);
> +       list_for_each_entry(c, &ti_clk_list, node) {
> +               int r = strncmp(c->lk->conn_id, clk_name, 32);
> +               pr_err("%s: searching %s in %s - %d\n",
> +                       __func__, clk_name, c->lk->con_id, r);
> +               if (!r) {
> +                       pr_err("%s: found it!\n", __func__);
> +                       return c->lk.clk;
> +               }
> +       }
> +#else
> +       /* Use integer indexing into clkdev list! Sigh.. */
> +       int idx = clkspec->args[0];
> +       int cindex = 1;
> +
> +       list_for_each_entry(c, &ti_clk_list, node) {
> +               int r = (idx == cindex) ? 0 :  1;
> +               pr_err("%s: searching index search = %d in %d in %s - %d\n",
> +                       __func__, idx, cindex, c->lk->con_id, r);
> +               if (!r) {
> +                       pr_err("%s: found it!\n", __func__);
> +                       return c->lk->clk;
> +               }
> +               cindex++;
> +       }
> +#endif
> +
> +       pr_err("%s: ran out of options\n", __func__);
> +       return ERR_PTR(-ENODEV);
> +}
> +
> +static void __init ti_clock_init(struct device_node *node)
> +{
> +
> +       pr_err("%s: START\n", __func__);
> +       of_clk_add_provider(node, ti_bypass_clk_get_by_name, NULL);
> +       pr_err("%s: END\n", __func__);
> +}
> +CLK_OF_DECLARE(ti_clk, "ti,clock", ti_clock_init);
> +
> +void __init ti_clk_node_add(struct clk_lookup *lk)
> +{
> +       struct ti_clk *c;
> +       static bool of_added;
> +
> +       c = kzalloc(sizeof(struct ti_clk), GFP_KERNEL);
> +       if (!c) {
> +               pr_err("%s: No memory!! cannot add clk node!\n", __func__);
> +               return;
> +       }
> +       clkdev_add(lk);
> +       c->lk = lk;
> +       list_add_tail(&c->node, &ti_clk_list);
> +       pr_err("%s: Added clock node %s\n", __func__, lk->con_id);
> +       if (!of_added) {
> +               of_clk_init(NULL);
> +               of_added =  true;
> +       }
> +};
> +
> diff --git a/include/linux/clk/ti.h b/include/linux/clk/ti.h
> new file mode 100644
> index 0000000..eb502a8
> --- /dev/null
> +++ b/include/linux/clk/ti.h
> @@ -0,0 +1,30 @@
> +/*
> + * TI Clock node provider header
> + *
> + * Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com/
> + *     Nishanth Menon
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> + * kind, whether express or implied; without even the implied warranty
> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +#ifndef __TI_CLK_H
> +#define __TI_CLK_H
> +
> +#include <linux/clkdev.h>
> +
> +#ifdef CONFIG_OF
> +extern void ti_clk_node_add(struct clk_lookup *lk);
> +#else
> +static inline void ti_clk_node_add(struct clk_lookup *lk)
> +{
> +       clkdev_add(lk);
> +}
> +#endif /* CONFIG_OF */
> +
> +#endif /* __TI_CLK_H */
> -- 
> 1.7.9.5
> 
> 
> -- 
> Regards,
> Nishanth Menon
> --
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