clk: at91: add slow clks driver

AT91 slow clk is a clk multiplexer.

In some SoCs (sam9x5, sama5, sam9g45 families) this multiplexer can
choose among 2 sources: an internal RC oscillator circuit and an oscillator
using an external crystal.

In other Socs (sam9260 family) the multiplexer source is hardcoded with
the OSCSEL signal.
Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

drivers/clk/at91/Makefile

@@ -2,8 +2,8 @@
 # Makefile for at91 specific clk
 #
 
-obj-y += pmc.o
-obj-y += clk-main.o clk-pll.o clk-plldiv.o clk-master.o
+obj-y += pmc.o sckc.o
+obj-y += clk-slow.o clk-main.o clk-pll.o clk-plldiv.o clk-master.o
 obj-y += clk-system.o clk-peripheral.o clk-programmable.o
 
 obj-$(CONFIG_HAVE_AT91_UTMI)		+= clk-utmi.o

drivers/clk/at91/pmc.c

@@ -229,6 +229,11 @@ static struct at91_pmc *__init at91_pmc_init(struct device_node *np,
 }
 
 static const struct of_device_id pmc_clk_ids[] __initconst = {
+	/* Slow oscillator */
+	{
+		.compatible = "atmel,at91sam9260-clk-slow",
+		.data = of_at91sam9260_clk_slow_setup,
+	},
 	/* Main clock */
 	{
 		.compatible = "atmel,at91rm9200-clk-main-osc",

drivers/clk/at91/pmc.h

@@ -58,6 +58,9 @@ static inline void pmc_write(struct at91_pmc *pmc, int offset, u32 value)
 int of_at91_get_clk_range(struct device_node *np, const char *propname,
 			  struct clk_range *range);
 
+extern void __init of_at91sam9260_clk_slow_setup(struct device_node *np,
+						 struct at91_pmc *pmc);
+
 extern void __init of_at91rm9200_clk_main_osc_setup(struct device_node *np,
 						    struct at91_pmc *pmc);
 extern void __init of_at91sam9x5_clk_main_rc_osc_setup(struct device_node *np,

drivers/clk/at91/sckc.c

+/*
+ * drivers/clk/at91/sckc.c
+ *
+ *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
+ *
+ * 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.
+ *
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/io.h>
+
+#include "sckc.h"
+
+static const struct of_device_id sckc_clk_ids[] __initconst = {
+	/* Slow clock */
+	{
+		.compatible = "atmel,at91sam9x5-clk-slow-osc",
+		.data = of_at91sam9x5_clk_slow_osc_setup,
+	},
+	{
+		.compatible = "atmel,at91sam9x5-clk-slow-rc-osc",
+		.data = of_at91sam9x5_clk_slow_rc_osc_setup,
+	},
+	{
+		.compatible = "atmel,at91sam9x5-clk-slow",
+		.data = of_at91sam9x5_clk_slow_setup,
+	},
+	{ /*sentinel*/ }
+};
+
+static void __init of_at91sam9x5_sckc_setup(struct device_node *np)
+{
+	struct device_node *childnp;
+	void (*clk_setup)(struct device_node *, void __iomem *);
+	const struct of_device_id *clk_id;
+	void __iomem *regbase = of_iomap(np, 0);
+
+	if (!regbase)
+		return;
+
+	for_each_child_of_node(np, childnp) {
+		clk_id = of_match_node(sckc_clk_ids, childnp);
+		if (!clk_id)
+			continue;
+		clk_setup = clk_id->data;
+		clk_setup(childnp, regbase);
+	}
+}
+CLK_OF_DECLARE(at91sam9x5_clk_sckc, "atmel,at91sam9x5-sckc",
+	       of_at91sam9x5_sckc_setup);

drivers/clk/at91/sckc.h

+/*
+ * drivers/clk/at91/sckc.h
+ *
+ *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
+ *
+ * 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.
+ */
+
+#ifndef __AT91_SCKC_H_
+#define __AT91_SCKC_H_
+
+extern void __init of_at91sam9x5_clk_slow_osc_setup(struct device_node *np,
+						    void __iomem *sckcr);
+extern void __init of_at91sam9x5_clk_slow_rc_osc_setup(struct device_node *np,
+						       void __iomem *sckcr);
+extern void __init of_at91sam9x5_clk_slow_setup(struct device_node *np,
+						void __iomem *sckcr);
+
+#endif /* __AT91_SCKC_H_ */

include/linux/clk/at91_pmc.h

@@ -155,6 +155,7 @@ extern void __iomem *at91_pmc_base;
 #define		AT91_PMC_LOCKB		(1 <<  2)		/* PLLB Lock */
 #define		AT91_PMC_MCKRDY		(1 <<  3)		/* Master Clock */
 #define		AT91_PMC_LOCKU		(1 <<  6)		/* UPLL Lock [some SAM9] */
+#define		AT91_PMC_OSCSEL		(1 <<  7)		/* Slow Oscillator Selection [some SAM9] */
 #define		AT91_PMC_PCK0RDY	(1 <<  8)		/* Programmable Clock 0 */
 #define		AT91_PMC_PCK1RDY	(1 <<  9)		/* Programmable Clock 1 */
 #define		AT91_PMC_PCK2RDY	(1 << 10)		/* Programmable Clock 2 */