diff options
author | Juergen Beisert <j.beisert@pengutronix.de> | 2008-07-05 10:02:47 +0200 |
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committer | Robert Schwebel <r.schwebel@pengutronix.de> | 2008-07-05 10:02:47 +0200 |
commit | c0db2ea4e366c94dd3f880928c02534156e3d1b9 (patch) | |
tree | e8486fedc9d405b2867c3a474ebc18fad394836c /arch/arm/plat-mxc/clock.c | |
parent | 38a41fdf94c449c165213e4665c3f8a0d30f8aba (diff) | |
download | linux-c0db2ea4e366c94dd3f880928c02534156e3d1b9.tar.bz2 |
MXC family: Add clock handling
Internal clock path handling for the mxc CPUs.
Changed against the original Freescale code (and against clocklib for example):
- clock rate is always calculated whenever one ask for the current rate
(means struct clk has no more a member called "rate"). So switching the PLL
base frequency will propagate immediately to all other clocks that are
depending on this frequency.
Signed-off-by: Juergen Beisert <j.beisert@pengutronix.de>
Diffstat (limited to 'arch/arm/plat-mxc/clock.c')
-rw-r--r-- | arch/arm/plat-mxc/clock.c | 331 |
1 files changed, 331 insertions, 0 deletions
diff --git a/arch/arm/plat-mxc/clock.c b/arch/arm/plat-mxc/clock.c new file mode 100644 index 000000000000..1aa86fd60d71 --- /dev/null +++ b/arch/arm/plat-mxc/clock.c @@ -0,0 +1,331 @@ +/* + * Based on arch/arm/plat-omap/clock.c + * + * Copyright (C) 2004 - 2005 Nokia corporation + * Written by Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com> + * Modified for omap shared clock framework by Tony Lindgren <tony@atomide.com> + * Copyright 2007 Freescale Semiconductor, Inc. All Rights Reserved. + * Copyright 2008 Juergen Beisert, kernel@pengutronix.de + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, + * MA 02110-1301, USA. + */ + +/* #define DEBUG */ + +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/errno.h> +#include <linux/init.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/platform_device.h> +#include <linux/proc_fs.h> +#include <linux/semaphore.h> +#include <linux/string.h> +#include <linux/version.h> + +#include <asm/arch/clock.h> + +static LIST_HEAD(clocks); +static DEFINE_MUTEX(clocks_mutex); + +/*------------------------------------------------------------------------- + * Standard clock functions defined in include/linux/clk.h + *-------------------------------------------------------------------------*/ + +/* + * Retrieve a clock by name. + * + * Note that we first try to use device id on the bus + * and clock name. If this fails, we try to use "<name>.<id>". If this fails, + * we try to use clock name only. + * The reference count to the clock's module owner ref count is incremented. + */ +struct clk *clk_get(struct device *dev, const char *id) +{ + struct clk *p, *clk = ERR_PTR(-ENOENT); + int idno; + const char *str; + + if (id == NULL) + return clk; + + if (dev == NULL || dev->bus != &platform_bus_type) + idno = -1; + else + idno = to_platform_device(dev)->id; + + mutex_lock(&clocks_mutex); + + list_for_each_entry(p, &clocks, node) { + if (p->id == idno && + strcmp(id, p->name) == 0 && try_module_get(p->owner)) { + clk = p; + goto found; + } + } + + str = strrchr(id, '.'); + if (str) { + int cnt = str - id; + str++; + idno = simple_strtol(str, NULL, 10); + list_for_each_entry(p, &clocks, node) { + if (p->id == idno && + strlen(p->name) == cnt && + strncmp(id, p->name, cnt) == 0 && + try_module_get(p->owner)) { + clk = p; + goto found; + } + } + } + + list_for_each_entry(p, &clocks, node) { + if (strcmp(id, p->name) == 0 && try_module_get(p->owner)) { + clk = p; + goto found; + } + } + + printk(KERN_WARNING "clk: Unable to get requested clock: %s\n", id); + +found: + mutex_unlock(&clocks_mutex); + + return clk; +} +EXPORT_SYMBOL(clk_get); + +static void __clk_disable(struct clk *clk) +{ + if (clk == NULL || IS_ERR(clk)) + return; + + __clk_disable(clk->parent); + __clk_disable(clk->secondary); + + if (!(--clk->usecount) && clk->disable) + clk->disable(clk); +} + +static int __clk_enable(struct clk *clk) +{ + if (clk == NULL || IS_ERR(clk)) + return -EINVAL; + + __clk_enable(clk->parent); + __clk_enable(clk->secondary); + + if (clk->usecount++ == 0 && clk->enable) + clk->enable(clk); + + return 0; +} + +/* This function increments the reference count on the clock and enables the + * clock if not already enabled. The parent clock tree is recursively enabled + */ +int clk_enable(struct clk *clk) +{ + int ret = 0; + + if (clk == NULL || IS_ERR(clk)) + return -EINVAL; + + mutex_lock(&clocks_mutex); + ret = __clk_enable(clk); + mutex_unlock(&clocks_mutex); + + return ret; +} +EXPORT_SYMBOL(clk_enable); + +/* This function decrements the reference count on the clock and disables + * the clock when reference count is 0. The parent clock tree is + * recursively disabled + */ +void clk_disable(struct clk *clk) +{ + if (clk == NULL || IS_ERR(clk)) + return; + + mutex_lock(&clocks_mutex); + __clk_disable(clk); + mutex_unlock(&clocks_mutex); +} +EXPORT_SYMBOL(clk_disable); + +/* Retrieve the *current* clock rate. If the clock itself + * does not provide a special calculation routine, ask + * its parent and so on, until one is able to return + * a valid clock rate + */ +unsigned long clk_get_rate(struct clk *clk) +{ + if (clk == NULL || IS_ERR(clk)) + return 0UL; + + if (clk->get_rate) + return clk->get_rate(clk); + + return clk_get_rate(clk->parent); +} +EXPORT_SYMBOL(clk_get_rate); + +/* Decrement the clock's module reference count */ +void clk_put(struct clk *clk) +{ + if (clk && !IS_ERR(clk)) + module_put(clk->owner); +} +EXPORT_SYMBOL(clk_put); + +/* Round the requested clock rate to the nearest supported + * rate that is less than or equal to the requested rate. + * This is dependent on the clock's current parent. + */ +long clk_round_rate(struct clk *clk, unsigned long rate) +{ + if (clk == NULL || IS_ERR(clk) || !clk->round_rate) + return 0; + + return clk->round_rate(clk, rate); +} +EXPORT_SYMBOL(clk_round_rate); + +/* Set the clock to the requested clock rate. The rate must + * match a supported rate exactly based on what clk_round_rate returns + */ +int clk_set_rate(struct clk *clk, unsigned long rate) +{ + int ret = -EINVAL; + + if (clk == NULL || IS_ERR(clk) || clk->set_rate == NULL || rate == 0) + return ret; + + mutex_lock(&clocks_mutex); + ret = clk->set_rate(clk, rate); + mutex_unlock(&clocks_mutex); + + return ret; +} +EXPORT_SYMBOL(clk_set_rate); + +/* Set the clock's parent to another clock source */ +int clk_set_parent(struct clk *clk, struct clk *parent) +{ + int ret = -EINVAL; + + if (clk == NULL || IS_ERR(clk) || parent == NULL || + IS_ERR(parent) || clk->set_parent == NULL) + return ret; + + mutex_lock(&clocks_mutex); + ret = clk->set_parent(clk, parent); + if (ret == 0) + clk->parent = parent; + mutex_unlock(&clocks_mutex); + + return ret; +} +EXPORT_SYMBOL(clk_set_parent); + +/* Retrieve the clock's parent clock source */ +struct clk *clk_get_parent(struct clk *clk) +{ + struct clk *ret = NULL; + + if (clk == NULL || IS_ERR(clk)) + return ret; + + return clk->parent; +} +EXPORT_SYMBOL(clk_get_parent); + +/* + * Add a new clock to the clock tree. + */ +int clk_register(struct clk *clk) +{ + if (clk == NULL || IS_ERR(clk)) + return -EINVAL; + + mutex_lock(&clocks_mutex); + list_add(&clk->node, &clocks); + mutex_unlock(&clocks_mutex); + + return 0; +} +EXPORT_SYMBOL(clk_register); + +/* Remove a clock from the clock tree */ +void clk_unregister(struct clk *clk) +{ + if (clk == NULL || IS_ERR(clk)) + return; + + mutex_lock(&clocks_mutex); + list_del(&clk->node); + mutex_unlock(&clocks_mutex); +} +EXPORT_SYMBOL(clk_unregister); + +#ifdef CONFIG_PROC_FS +static int mxc_clock_read_proc(char *page, char **start, off_t off, + int count, int *eof, void *data) +{ + struct clk *clkp; + char *p = page; + int len; + + list_for_each_entry(clkp, &clocks, node) { + p += sprintf(p, "%s-%d:\t\t%lu, %d", clkp->name, clkp->id, + clk_get_rate(clkp), clkp->usecount); + if (clkp->parent) + p += sprintf(p, ", %s-%d\n", clkp->parent->name, + clkp->parent->id); + else + p += sprintf(p, "\n"); + } + + len = (p - page) - off; + if (len < 0) + len = 0; + + *eof = (len <= count) ? 1 : 0; + *start = page + off; + + return len; +} + +static int __init mxc_setup_proc_entry(void) +{ + struct proc_dir_entry *res; + + res = create_proc_read_entry("cpu/clocks", 0, NULL, + mxc_clock_read_proc, NULL); + if (!res) { + printk(KERN_ERR "Failed to create proc/cpu/clocks\n"); + return -ENOMEM; + } + return 0; +} + +late_initcall(mxc_setup_proc_entry); +#endif |