From e59c5371fb9d8268d1c043172e88cecab9dc934f Mon Sep 17 00:00:00 2001 From: Mike Turquette Date: Tue, 18 Feb 2014 21:21:25 -0800 Subject: clk: introduce clk_set_phase function & callback A common operation for a clock signal generator is to shift the phase of that signal. This patch introduces a new function to the clk.h API to dynamically adjust the phase of a clock signal. Additionally this patch introduces support for the new function in the common clock framework via the .set_phase call back in struct clk_ops. Signed-off-by: Mike Turquette Signed-off-by: Maxime Ripard Reviewed-by: Heiko Stuebner Acked-by: Hans de Goede --- drivers/clk/clk.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 81 insertions(+), 4 deletions(-) (limited to 'drivers/clk/clk.c') diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index b76fa69b44cb..d87661af0c72 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -117,11 +117,11 @@ static void clk_summary_show_one(struct seq_file *s, struct clk *c, int level) if (!c) return; - seq_printf(s, "%*s%-*s %11d %12d %11lu %10lu\n", + seq_printf(s, "%*s%-*s %11d %12d %11lu %10lu %-3d\n", level * 3 + 1, "", 30 - level * 3, c->name, c->enable_count, c->prepare_count, clk_get_rate(c), - clk_get_accuracy(c)); + clk_get_accuracy(c), clk_get_phase(c)); } static void clk_summary_show_subtree(struct seq_file *s, struct clk *c, @@ -143,8 +143,8 @@ static int clk_summary_show(struct seq_file *s, void *data) struct clk *c; struct hlist_head **lists = (struct hlist_head **)s->private; - seq_puts(s, " clock enable_cnt prepare_cnt rate accuracy\n"); - seq_puts(s, "--------------------------------------------------------------------------------\n"); + seq_puts(s, " clock enable_cnt prepare_cnt rate accuracy phase\n"); + seq_puts(s, "----------------------------------------------------------------------------------------\n"); clk_prepare_lock(); @@ -180,6 +180,7 @@ static void clk_dump_one(struct seq_file *s, struct clk *c, int level) seq_printf(s, "\"prepare_count\": %d,", c->prepare_count); seq_printf(s, "\"rate\": %lu", clk_get_rate(c)); seq_printf(s, "\"accuracy\": %lu", clk_get_accuracy(c)); + seq_printf(s, "\"phase\": %d", clk_get_phase(c)); } static void clk_dump_subtree(struct seq_file *s, struct clk *c, int level) @@ -264,6 +265,11 @@ static int clk_debug_create_one(struct clk *clk, struct dentry *pdentry) if (!d) goto err_out; + d = debugfs_create_u32("clk_phase", S_IRUGO, clk->dentry, + (u32 *)&clk->phase); + if (!d) + goto err_out; + d = debugfs_create_x32("clk_flags", S_IRUGO, clk->dentry, (u32 *)&clk->flags); if (!d) @@ -1738,6 +1744,77 @@ out: } EXPORT_SYMBOL_GPL(clk_set_parent); +/** + * clk_set_phase - adjust the phase shift of a clock signal + * @clk: clock signal source + * @degrees: number of degrees the signal is shifted + * + * Shifts the phase of a clock signal by the specified + * degrees. Returns 0 on success, -EERROR otherwise. + * + * This function makes no distinction about the input or reference + * signal that we adjust the clock signal phase against. For example + * phase locked-loop clock signal generators we may shift phase with + * respect to feedback clock signal input, but for other cases the + * clock phase may be shifted with respect to some other, unspecified + * signal. + * + * Additionally the concept of phase shift does not propagate through + * the clock tree hierarchy, which sets it apart from clock rates and + * clock accuracy. A parent clock phase attribute does not have an + * impact on the phase attribute of a child clock. + */ +int clk_set_phase(struct clk *clk, int degrees) +{ + int ret = 0; + + if (!clk) + goto out; + + /* sanity check degrees */ + degrees %= 360; + if (degrees < 0) + degrees += 360; + + clk_prepare_lock(); + + if (!clk->ops->set_phase) + goto out_unlock; + + ret = clk->ops->set_phase(clk->hw, degrees); + + if (!ret) + clk->phase = degrees; + +out_unlock: + clk_prepare_unlock(); + +out: + return ret; +} + +/** + * clk_get_phase - return the phase shift of a clock signal + * @clk: clock signal source + * + * Returns the phase shift of a clock node in degrees, otherwise returns + * -EERROR. + */ +int clk_get_phase(struct clk *clk) +{ + int ret = 0; + + if (!clk) + goto out; + + clk_prepare_lock(); + ret = clk->phase; + clk_prepare_unlock(); + +out: + return ret; +} + /** * __clk_init - initialize the data structures in a struct clk * @dev: device initializing this clk, placeholder for now -- cgit v1.2.3