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ARM: bcm2835: add stub clock driver

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This patch adds a minimal stub clock driver for the BCM2835. Its sole
purpose is to allow the PL011 AMBA clk_get() API calls to provide
something that looks enough like a clock that the driver probes and
operates correctly.

This patch was extracted from git://github.com/lp0/linux.git branch
rpi-split as of 2012/09/08, and modified as follows:

* Reworked to call clk_register_fixed_rate(), and clk_register_clkdev()
  rather than using static data to represent the clocks.
* Moved implementation to drivers/clk/.
* Modified .dev_id for UART clocks to match UART DT node names.
* s/bcm2708/bcm2835/.
* Modified device tree vendor prefix.

Signed-off-by: Chris Boot <bootc@bootc.net>
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Signed-off-by: Dom Cobley <dc4@broadcom.com>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Mike Turquette <mturquette@linaro.org>
This commit is contained in:
Simon Arlott 2012-09-10 23:26:15 -06:00 committed by Stephen Warren
parent ee4af56967
commit 75fabc3f64
4 changed files with 87 additions and 0 deletions
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3
arch/arm/mach-bcm2835/bcm2835.c
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@ -16,6 +16,7 @@
#include <linux/irqchip/bcm2835.h>
#include <linux/of_platform.h>
#include <linux/bcm2835_timer.h>
#include <linux/clk/bcm2835.h>
#include <asm/mach/arch.h>
#include <asm/mach/map.h>
@ -38,6 +39,8 @@ void __init bcm2835_init(void)
{
int ret;
bcm2835_init_clocks();
ret = of_platform_populate(NULL, of_default_bus_match_table, NULL,
NULL);
if (ret) {

1
drivers/clk/Makefile
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@ -3,6 +3,7 @@ obj-$(CONFIG_CLKDEV_LOOKUP) += clkdev.o
obj-$(CONFIG_COMMON_CLK) += clk.o clk-fixed-rate.o clk-gate.o \
clk-mux.o clk-divider.o clk-fixed-factor.o
# SoCs specific
obj-$(CONFIG_ARCH_BCM2835) += clk-bcm2835.o
obj-$(CONFIG_ARCH_NOMADIK) += clk-nomadik.o
obj-$(CONFIG_ARCH_HIGHBANK) += clk-highbank.o
obj-$(CONFIG_ARCH_MXS) += mxs/

59
drivers/clk/clk-bcm2835.c Normal file
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@ -0,0 +1,59 @@
/*
* Copyright (C) 2010 Broadcom
* Copyright (C) 2012 Stephen Warren
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/clk-provider.h>
#include <linux/clkdev.h>
#include <linux/clk/bcm2835.h>
/*
* These are fixed clocks. They're probably not all root clocks and it may
* be possible to turn them on and off but until this is mapped out better
* it's the only way they can be used.
*/
void __init bcm2835_init_clocks(void)
{
struct clk *clk;
int ret;
clk = clk_register_fixed_rate(NULL, "sys_pclk", NULL, CLK_IS_ROOT,
250000000);
if (!clk)
pr_err("sys_pclk not registered\n");
clk = clk_register_fixed_rate(NULL, "apb_pclk", NULL, CLK_IS_ROOT,
126000000);
if (!clk)
pr_err("apb_pclk not registered\n");
clk = clk_register_fixed_rate(NULL, "uart0_pclk", NULL, CLK_IS_ROOT,
3000000);
if (!clk)
pr_err("uart0_pclk not registered\n");
ret = clk_register_clkdev(clk, NULL, "20201000.uart");
if (ret)
pr_err("uart0_pclk alias not registered\n");
clk = clk_register_fixed_rate(NULL, "uart1_pclk", NULL, CLK_IS_ROOT,
125000000);
if (!clk)
pr_err("uart1_pclk not registered\n");
ret = clk_register_clkdev(clk, NULL, "20215000.uart");
if (ret)
pr_err("uart0_pclk alias not registered\n");
}

24
include/linux/clk/bcm2835.h Normal file
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@ -0,0 +1,24 @@
/*
* Copyright (C) 2010 Broadcom
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef __LINUX_CLK_BCM2835_H_
#define __LINUX_CLK_BCM2835_H_
void __init bcm2835_init_clocks(void);
#endif