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Message-Id: <1401209816-24953-1-git-send-email-elder@linaro.org>
Date: Tue, 27 May 2014 11:56:56 -0500
From: Alex Elder <elder@...aro.org>
To: mturquette@...aro.org, mporter@...aro.org, bcm@...thebug.org
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] clk: bcm/kona: implement determine_rate()
Implement the clk->determine_rate method for Broadcom Kona peripheral
clocks. This allows a peripheral clock to be re-parented in order to
satisfy a rate change request. This takes the place of the previous
kona_peri_clk_round_rate() functionality, though that function remains
because it is used by the new one.
The parent clock that allows the peripheral clock to produce a rate
closest to the one requested is the one selected, though the current
parent is used by default.
Signed-off-by: Alex Elder <elder@...aro.org>
---
v2: Added WARN_ON_ONCE() call as suggested.
This patch is based on Mike Turquette's current "clk-next" branch.
42dd880 Merge branch 'clk-fixes' into clk-next
It is available here:
http://git.linaro.org/landing-teams/working/broadcom/kernel.git
Branch review/bcm-determine-rate-v2
drivers/clk/bcm/clk-kona.c | 54 +++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 53 insertions(+), 1 deletion(-)
diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c
index d603c4e..95af2e6 100644
--- a/drivers/clk/bcm/clk-kona.c
+++ b/drivers/clk/bcm/clk-kona.c
@@ -1031,6 +1031,58 @@ static long kona_peri_clk_round_rate(struct clk_hw *hw, unsigned long rate,
rate ? rate : 1, *parent_rate, NULL);
}
+static long kona_peri_clk_determine_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *best_parent_rate, struct clk **best_parent)
+{
+ struct kona_clk *bcm_clk = to_kona_clk(hw);
+ struct clk *clk = hw->clk;
+ struct clk *current_parent;
+ unsigned long parent_rate;
+ unsigned long best_delta;
+ unsigned long best_rate;
+ u32 parent_count;
+ u32 which;
+
+ /*
+ * If there is no other parent to choose, use the current one.
+ * Note: We don't honor (or use) CLK_SET_RATE_NO_REPARENT.
+ */
+ WARN_ON_ONCE(bcm_clk->init_data.flags & CLK_SET_RATE_NO_REPARENT);
+ parent_count = (u32)bcm_clk->init_data.num_parents;
+ if (parent_count < 2)
+ return kona_peri_clk_round_rate(hw, rate, best_parent_rate);
+
+ /* Unless we can do better, stick with current parent */
+ current_parent = clk_get_parent(clk);
+ parent_rate = __clk_get_rate(current_parent);
+ best_rate = kona_peri_clk_round_rate(hw, rate, &parent_rate);
+ best_delta = abs(best_rate - rate);
+
+ /* Check whether any other parent clock can produce a better result */
+ for (which = 0; which < parent_count; which++) {
+ struct clk *parent = clk_get_parent_by_index(clk, which);
+ unsigned long delta;
+ unsigned long other_rate;
+
+ BUG_ON(!parent);
+ if (parent == current_parent)
+ continue;
+
+ /* We don't support CLK_SET_RATE_PARENT */
+ parent_rate = __clk_get_rate(parent);
+ other_rate = kona_peri_clk_round_rate(hw, rate, &parent_rate);
+ delta = abs(other_rate - rate);
+ if (delta < best_delta) {
+ best_delta = delta;
+ best_rate = other_rate;
+ *best_parent = parent;
+ *best_parent_rate = parent_rate;
+ }
+ }
+
+ return best_rate;
+}
+
static int kona_peri_clk_set_parent(struct clk_hw *hw, u8 index)
{
struct kona_clk *bcm_clk = to_kona_clk(hw);
@@ -1135,7 +1187,7 @@ struct clk_ops kona_peri_clk_ops = {
.disable = kona_peri_clk_disable,
.is_enabled = kona_peri_clk_is_enabled,
.recalc_rate = kona_peri_clk_recalc_rate,
- .round_rate = kona_peri_clk_round_rate,
+ .determine_rate = kona_peri_clk_determine_rate,
.set_parent = kona_peri_clk_set_parent,
.get_parent = kona_peri_clk_get_parent,
.set_rate = kona_peri_clk_set_rate,
--
1.9.1
--
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