diff options
Diffstat (limited to 'arch/metag/kernel/clock.c')
-rw-r--r-- | arch/metag/kernel/clock.c | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/arch/metag/kernel/clock.c b/arch/metag/kernel/clock.c new file mode 100644 index 000000000..6339c9c6d --- /dev/null +++ b/arch/metag/kernel/clock.c @@ -0,0 +1,110 @@ +/* + * arch/metag/kernel/clock.c + * + * Copyright (C) 2012 Imagination Technologies Ltd. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/io.h> +#include <linux/of.h> + +#include <asm/param.h> +#include <asm/clock.h> + +struct meta_clock_desc _meta_clock; + +/* Default machine get_core_freq callback. */ +static unsigned long get_core_freq_default(void) +{ +#ifdef CONFIG_METAG_META21 + /* + * Meta 2 cores divide down the core clock for the Meta timers, so we + * can estimate the core clock from the divider. + */ + return (metag_in32(EXPAND_TIMER_DIV) + 1) * 1000000; +#else + /* + * On Meta 1 we don't know the core clock, but assuming the Meta timer + * is correct it can be estimated based on loops_per_jiffy. + */ + return (loops_per_jiffy * HZ * 5) >> 1; +#endif +} + +static struct clk *clk_core; + +/* Clk based get_core_freq callback. */ +static unsigned long get_core_freq_clk(void) +{ + return clk_get_rate(clk_core); +} + +/** + * init_metag_core_clock() - Set up core clock from devicetree. + * + * Checks to see if a "core" clock is provided in the device tree, and overrides + * the get_core_freq callback to use it. + */ +static void __init init_metag_core_clock(void) +{ + /* + * See if a core clock is provided by the devicetree (and + * registered by the init callback above). + */ + struct device_node *node; + node = of_find_compatible_node(NULL, NULL, "img,meta"); + if (!node) { + pr_warn("%s: no compatible img,meta DT node found\n", + __func__); + return; + } + + clk_core = of_clk_get_by_name(node, "core"); + if (IS_ERR(clk_core)) { + pr_warn("%s: no core clock found in DT\n", + __func__); + return; + } + + /* + * Override the core frequency callback to use + * this clk. + */ + _meta_clock.get_core_freq = get_core_freq_clk; +} + +/** + * init_metag_clocks() - Set up clocks from devicetree. + * + * Set up important clocks from device tree. In particular any needed for clock + * sources. + */ +void __init init_metag_clocks(void) +{ + init_metag_core_clock(); + + pr_info("Core clock frequency: %lu Hz\n", get_coreclock()); +} + +/** + * setup_meta_clocks() - Early set up of the Meta clock. + * @desc: Clock descriptor usually provided by machine description + * + * Ensures all callbacks are valid. + */ +void __init setup_meta_clocks(struct meta_clock_desc *desc) +{ + /* copy callbacks */ + if (desc) + _meta_clock = *desc; + + /* set fallback functions */ + if (!_meta_clock.get_core_freq) + _meta_clock.get_core_freq = get_core_freq_default; +} + |