ARM: bcm2835: add stub clock driver

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>

4 files changed, 87 insertions, 0 deletions

diff --git a/arch/arm/mach-bcm2835/bcm2835.c b/arch/arm/mach-bcm2835/bcm2835.c
index e3f296860dd0..f6fea4933571 100644
--- a/arch/arm/mach-bcm2835/bcm2835.c
+++ b/arch/arm/mach-bcm2835/bcm2835.c
@@ -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) {
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 5869ea387054..d5c19d1e0cf8 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -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/
diff --git a/drivers/clk/clk-bcm2835.c b/drivers/clk/clk-bcm2835.c
new file mode 100644
index 000000000000..67ad16b20b81
--- /dev/null
+++ b/drivers/clk/clk-bcm2835.c
@@ -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");
+}
diff --git a/include/linux/clk/bcm2835.h b/include/linux/clk/bcm2835.h
new file mode 100644
index 000000000000..aa937f6c17da
--- /dev/null
+++ b/include/linux/clk/bcm2835.h
@@ -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