clk: add clock protection mechanism to clk core
The patch adds clk_core_protect and clk_core_unprotect to the internal CCF API. These functions allow to set a new constraint along the clock tree to prevent any change, even indirect, which may result in rate change or glitch. Tested-by: Maxime Ripard <maxime.ripard@free-electrons.com> Acked-by: Michael Turquette <mturquette@baylibre.com> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com> Signed-off-by: Michael Turquette <mturquette@baylibre.com> Link: lkml.kernel.org/r/20171201215200.23523-7-jbrunet@baylibre.comhifive-unleashed-5.1
Jerome Brunet
Michael Turquette
parent
ca5e089a32
commit
e55a839a7a
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@ -62,6 +62,7 @@ struct clk_core {
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bool orphan;
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unsigned int enable_count;
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unsigned int prepare_count;
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unsigned int protect_count;
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unsigned long min_rate;
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unsigned long max_rate;
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unsigned long accuracy;
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@ -170,6 +171,11 @@ static void clk_enable_unlock(unsigned long flags)
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spin_unlock_irqrestore(&enable_lock, flags);
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}
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static bool clk_core_rate_is_protected(struct clk_core *core)
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{
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return core->protect_count;
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}
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static bool clk_core_is_prepared(struct clk_core *core)
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{
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bool ret = false;
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@ -381,6 +387,11 @@ bool clk_hw_is_prepared(const struct clk_hw *hw)
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return clk_core_is_prepared(hw->core);
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}
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bool clk_hw_rate_is_protected(const struct clk_hw *hw)
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{
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return clk_core_rate_is_protected(hw->core);
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}
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bool clk_hw_is_enabled(const struct clk_hw *hw)
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{
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return clk_core_is_enabled(hw->core);
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@ -519,6 +530,68 @@ EXPORT_SYMBOL_GPL(__clk_mux_determine_rate_closest);
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/*** clk api ***/
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static void clk_core_rate_unprotect(struct clk_core *core)
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{
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lockdep_assert_held(&prepare_lock);
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if (!core)
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return;
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if (WARN_ON(core->protect_count == 0))
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return;
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if (--core->protect_count > 0)
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return;
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clk_core_rate_unprotect(core->parent);
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}
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static int clk_core_rate_nuke_protect(struct clk_core *core)
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{
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int ret;
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lockdep_assert_held(&prepare_lock);
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if (!core)
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return -EINVAL;
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if (core->protect_count == 0)
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return 0;
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ret = core->protect_count;
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core->protect_count = 1;
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clk_core_rate_unprotect(core);
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return ret;
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}
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static void clk_core_rate_protect(struct clk_core *core)
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{
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lockdep_assert_held(&prepare_lock);
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if (!core)
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return;
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if (core->protect_count == 0)
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clk_core_rate_protect(core->parent);
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core->protect_count++;
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}
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static void clk_core_rate_restore_protect(struct clk_core *core, int count)
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{
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lockdep_assert_held(&prepare_lock);
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if (!core)
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return;
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if (count == 0)
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return;
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clk_core_rate_protect(core);
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core->protect_count = count;
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}
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static void clk_core_unprepare(struct clk_core *core)
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{
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lockdep_assert_held(&prepare_lock);
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@ -915,7 +988,9 @@ static int clk_core_determine_round_nolock(struct clk_core *core,
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if (!core)
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return 0;
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if (core->ops->determine_rate) {
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if (clk_core_rate_is_protected(core)) {
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req->rate = core->rate;
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} else if (core->ops->determine_rate) {
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return core->ops->determine_rate(core->hw, req);
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} else if (core->ops->round_rate) {
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rate = core->ops->round_rate(core->hw, req->rate,
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@ -1661,7 +1736,7 @@ static void clk_change_rate(struct clk_core *core)
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static unsigned long clk_core_req_round_rate_nolock(struct clk_core *core,
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unsigned long req_rate)
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{
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int ret;
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int ret, cnt;
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struct clk_rate_request req;
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lockdep_assert_held(&prepare_lock);
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@ -1669,11 +1744,19 @@ static unsigned long clk_core_req_round_rate_nolock(struct clk_core *core,
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if (!core)
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return 0;
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/* simulate what the rate would be if it could be freely set */
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cnt = clk_core_rate_nuke_protect(core);
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if (cnt < 0)
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return cnt;
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clk_core_get_boundaries(core, &req.min_rate, &req.max_rate);
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req.rate = req_rate;
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ret = clk_core_round_rate_nolock(core, &req);
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/* restore the protection */
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clk_core_rate_restore_protect(core, cnt);
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return ret ? 0 : req.rate;
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}
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@ -1693,6 +1776,10 @@ static int clk_core_set_rate_nolock(struct clk_core *core,
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if (rate == clk_core_get_rate_nolock(core))
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return 0;
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/* fail on a direct rate set of a protected provider */
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if (clk_core_rate_is_protected(core))
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return -EBUSY;
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if ((core->flags & CLK_SET_RATE_GATE) && core->prepare_count)
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return -EBUSY;
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@ -1937,6 +2024,9 @@ static int clk_core_set_parent_nolock(struct clk_core *core,
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if ((core->flags & CLK_SET_PARENT_GATE) && core->prepare_count)
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return -EBUSY;
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if (clk_core_rate_is_protected(core))
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return -EBUSY;
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/* try finding the new parent index */
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if (parent) {
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p_index = clk_fetch_parent_index(core, parent);
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@ -2018,6 +2108,9 @@ static int clk_core_set_phase_nolock(struct clk_core *core, int degrees)
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if (!core)
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return 0;
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if (clk_core_rate_is_protected(core))
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return -EBUSY;
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trace_clk_set_phase(core, degrees);
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if (core->ops->set_phase)
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@ -2148,11 +2241,12 @@ static void clk_summary_show_one(struct seq_file *s, struct clk_core *c,
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if (!c)
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return;
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seq_printf(s, "%*s%-*s %11d %12d %11lu %10lu %-3d\n",
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seq_printf(s, "%*s%-*s %11d %12d %12d %11lu %10lu %-3d\n",
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level * 3 + 1, "",
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30 - level * 3, c->name,
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c->enable_count, c->prepare_count, clk_core_get_rate(c),
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clk_core_get_accuracy(c), clk_core_get_phase(c));
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c->enable_count, c->prepare_count, c->protect_count,
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clk_core_get_rate(c), clk_core_get_accuracy(c),
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clk_core_get_phase(c));
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}
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static void clk_summary_show_subtree(struct seq_file *s, struct clk_core *c,
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@ -2174,8 +2268,8 @@ static int clk_summary_show(struct seq_file *s, void *data)
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struct clk_core *c;
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struct hlist_head **lists = (struct hlist_head **)s->private;
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seq_puts(s, " clock enable_cnt prepare_cnt rate accuracy phase\n");
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seq_puts(s, "----------------------------------------------------------------------------------------\n");
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seq_puts(s, " clock enable_cnt prepare_cnt protect_cnt rate accuracy phase\n");
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seq_puts(s, "----------------------------------------------------------------------------------------------------\n");
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clk_prepare_lock();
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@ -2210,6 +2304,7 @@ static void clk_dump_one(struct seq_file *s, struct clk_core *c, int level)
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seq_printf(s, "\"%s\": { ", c->name);
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seq_printf(s, "\"enable_count\": %d,", c->enable_count);
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seq_printf(s, "\"prepare_count\": %d,", c->prepare_count);
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seq_printf(s, "\"protect_count\": %d,", c->protect_count);
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seq_printf(s, "\"rate\": %lu,", clk_core_get_rate(c));
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seq_printf(s, "\"accuracy\": %lu,", clk_core_get_accuracy(c));
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seq_printf(s, "\"phase\": %d", clk_core_get_phase(c));
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@ -2340,6 +2435,11 @@ static int clk_debug_create_one(struct clk_core *core, struct dentry *pdentry)
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if (!d)
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goto err_out;
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d = debugfs_create_u32("clk_protect_count", S_IRUGO, core->dentry,
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(u32 *)&core->protect_count);
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if (!d)
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goto err_out;
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d = debugfs_create_u32("clk_notifier_count", S_IRUGO, core->dentry,
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(u32 *)&core->notifier_count);
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if (!d)
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@ -2911,6 +3011,11 @@ void clk_unregister(struct clk *clk)
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if (clk->core->prepare_count)
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pr_warn("%s: unregistering prepared clock: %s\n",
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__func__, clk->core->name);
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if (clk->core->protect_count)
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pr_warn("%s: unregistering protected clock: %s\n",
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__func__, clk->core->name);
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kref_put(&clk->core->ref, __clk_release);
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unlock:
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clk_prepare_unlock();
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@ -744,6 +744,7 @@ unsigned long clk_hw_get_rate(const struct clk_hw *hw);
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unsigned long __clk_get_flags(struct clk *clk);
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unsigned long clk_hw_get_flags(const struct clk_hw *hw);
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bool clk_hw_is_prepared(const struct clk_hw *hw);
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bool clk_hw_rate_is_protected(const struct clk_hw *hw);
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bool clk_hw_is_enabled(const struct clk_hw *hw);
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bool __clk_is_enabled(struct clk *clk);
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struct clk *__clk_lookup(const char *name);
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