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[V5,4/5] ARM: bcm2835: add stub clock driver

Message ID 1347690093-16910-4-git-send-email-swarren@wwwdotorg.org (mailing list archive)
State New, archived
Headers show

Commit Message

Stephen Warren Sept. 15, 2012, 6:21 a.m. UTC 
From: Simon Arlott <simon@fire.lp0.eu>

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:

* s/bcm2708/bcm2835/.
* Modified device tree vendor prefix.
* Moved implementation to drivers/clk/.
* Modified .dev_id for UART clocks to match UART DT node names.

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>
Cc: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
--
v5:
* No change.
v4:
* Moved implementation to drivers/clk/.
* s/bcm2708/bcm2835/.
* Updated for new device tree vendor prefix.
v3:
* New patch.
---
 arch/arm/mach-bcm2835/bcm2835.c |    3 +++
 drivers/clk/Makefile            |    1 +
 drivers/clk/clk-bcm2835.c       |   52 +++++++++++++++++++++++++++++++++++++++
 include/linux/clk/bcm2835.h     |   24 ++++++++++++++++++
 4 files changed, 80 insertions(+)
 create mode 100644 drivers/clk/clk-bcm2835.c
 create mode 100644 include/linux/clk/bcm2835.h

Comments

Mike Turquette Sept. 18, 2012, 5:31 p.m. UTC | #1 
Quoting Stephen Warren (2012-09-14 23:21:32)
> diff --git a/drivers/clk/clk-bcm2835.c b/drivers/clk/clk-bcm2835.c
> new file mode 100644
> index 0000000..148ac35
> --- /dev/null
> +++ b/drivers/clk/clk-bcm2835.c
> @@ -0,0 +1,52 @@
> +/*
> + * 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
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/clk-private.h>
> +#include <linux/clk-provider.h>

No need to include clk-provider.h or clk.h if you pull in clk-private.h.

Do you really need clk-private.h?  I really hate that approach and I'm
trying to minimize the number of platforms using those interfaces.  I
plan to delete clk-private.h once OMAP and Tegra move away from
statically initialized clocks needed during early boot.

> +#include <linux/clkdev.h>
> +#include <linux/clk/bcm2835.h>
> +
> +/*
> + * These are fixed clocks (and device tree doesn't support clk!).
> + *
> + * 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.
> + */
> +DEFINE_CLK_FIXED_RATE(sys_pclk,   CLK_IS_ROOT, 250000000, 0);
> +DEFINE_CLK_FIXED_RATE(apb_pclk,   CLK_IS_ROOT, 126000000, 0);
> +DEFINE_CLK_FIXED_RATE(uart0_pclk, CLK_IS_ROOT,   3000000, 0);
> +DEFINE_CLK_FIXED_RATE(uart1_pclk, CLK_IS_ROOT, 125000000, 0);
> +

How about:

clk_register_fixed_rate(NULL, "sys_pclk", NULL, CLK_IS_ROOT, 250000000);

Regards,
Mike
diff mbox

Patch

diff --git a/arch/arm/mach-bcm2835/bcm2835.c b/arch/arm/mach-bcm2835/bcm2835.c
index e3f2968..f6fea49 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 5869ea3..d5c19d1 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 0000000..148ac35
--- /dev/null
+++ b/drivers/clk/clk-bcm2835.c
@@ -0,0 +1,52 @@ 
+/*
+ * 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
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-private.h>
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/clk/bcm2835.h>
+
+/*
+ * These are fixed clocks (and device tree doesn't support clk!).
+ *
+ * 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.
+ */
+DEFINE_CLK_FIXED_RATE(sys_pclk,   CLK_IS_ROOT, 250000000, 0);
+DEFINE_CLK_FIXED_RATE(apb_pclk,   CLK_IS_ROOT, 126000000, 0);
+DEFINE_CLK_FIXED_RATE(uart0_pclk, CLK_IS_ROOT,   3000000, 0);
+DEFINE_CLK_FIXED_RATE(uart1_pclk, CLK_IS_ROOT, 125000000, 0);
+
+static struct clk_lookup lookups[] = {
+	{ .con_id = "sys_pclk", .clk = &sys_pclk },
+	{ .con_id = "apb_pclk", .clk = &apb_pclk },
+	{ .dev_id = "20201000.uart", .clk = &uart0_pclk },
+	{ .dev_id = "20215000.uart", .clk = &uart1_pclk }
+};
+
+void __init bcm2835_init_clocks(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(lookups); i++) {
+		__clk_init(NULL, lookups[i].clk);
+		clkdev_add(&lookups[i]);
+	}
+}
diff --git a/include/linux/clk/bcm2835.h b/include/linux/clk/bcm2835.h
new file mode 100644
index 0000000..aa937f6
--- /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