clk: change clk_ops' ->determine_rate() prototype

Clock rates are stored in an unsigned long field, but ->determine_rate()
(which returns a rounded rate from a requested one) returns a long
value (errors are reported using negative error codes), which can lead
to long overflow if the clock rate exceed 2Ghz.

Change ->determine_rate() prototype to return 0 or an error code, and pass
a pointer to a clk_rate_request structure containing the expected target
rate and the rate constraints imposed by clk users.

The clk_rate_request structure might be extended in the future to contain
other kind of constraints like the rounding policy, the maximum clock
inaccuracy or other things that are not yet supported by the CCF
(power consumption constraints ?).

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
CC: Jonathan Corbet <corbet@lwn.net>
CC: Tony Lindgren <tony@atomide.com>
CC: Ralf Baechle <ralf@linux-mips.org>
CC: "Emilio López" <emilio@elopez.com.ar>
CC: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Tero Kristo <t-kristo@ti.com>
CC: Peter De Schrijver <pdeschrijver@nvidia.com>
CC: Prashant Gaikwad <pgaikwad@nvidia.com>
CC: Stephen Warren <swarren@wwwdotorg.org>
CC: Thierry Reding <thierry.reding@gmail.com>
CC: Alexandre Courbot <gnurou@gmail.com>
CC: linux-doc@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: linux-arm-kernel@lists.infradead.org
CC: linux-omap@vger.kernel.org
CC: linux-mips@linux-mips.org
CC: linux-tegra@vger.kernel.org
[sboyd@codeaurora.org: Fix parent dereference problem in
__clk_determine_rate()]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Tested-by: Romain Perier <romain.perier@gmail.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
[sboyd@codeaurora.org: Folded in fix from Heiko for fixed-rate
clocks without parents or a rate determining op]
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

1 files changed, 21 insertions, 13 deletions

diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c
index 79a98506c433..d9c039c1902c 100644
--- a/drivers/clk/bcm/clk-kona.c
+++ b/drivers/clk/bcm/clk-kona.c
@@ -1017,10 +1017,8 @@ 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 min_rate,
-		unsigned long max_rate,
-		unsigned long *best_parent_rate, struct clk_hw **best_parent)
+static int kona_peri_clk_determine_rate(struct clk_hw *hw,
+					struct clk_rate_request *req)
 {
 	struct kona_clk *bcm_clk = to_kona_clk(hw);
 	struct clk *clk = hw->clk;
@@ -1029,6 +1027,7 @@ static long kona_peri_clk_determine_rate(struct clk_hw *hw, unsigned long rate,
 	unsigned long best_delta;
 	unsigned long best_rate;
 	u32 parent_count;
+	long rate;
 	u32 which;
 
 	/*
@@ -1037,14 +1036,21 @@ static long kona_peri_clk_determine_rate(struct clk_hw *hw, unsigned long rate,
 	 */
 	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);
+	if (parent_count < 2) {
+		rate = kona_peri_clk_round_rate(hw, req->rate,
+						&req->best_parent_rate);
+		if (rate < 0)
+			return rate;
+
+		req->rate = rate;
+		return 0;
+	}
 
 	/* 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);
+	best_rate = kona_peri_clk_round_rate(hw, req->rate, &parent_rate);
+	best_delta = abs(best_rate - req->rate);
 
 	/* Check whether any other parent clock can produce a better result */
 	for (which = 0; which < parent_count; which++) {
@@ -1058,17 +1064,19 @@ static long kona_peri_clk_determine_rate(struct clk_hw *hw, unsigned long rate,
 
 		/* 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);
+		other_rate = kona_peri_clk_round_rate(hw, req->rate,
+						      &parent_rate);
+		delta = abs(other_rate - req->rate);
 		if (delta < best_delta) {
 			best_delta = delta;
 			best_rate = other_rate;
-			*best_parent = __clk_get_hw(parent);
-			*best_parent_rate = parent_rate;
+			req->best_parent_hw = __clk_get_hw(parent);
+			req->best_parent_rate = parent_rate;
 		}
 	}
 
-	return best_rate;
+	req->rate = best_rate;
+	return 0;
 }
 
 static int kona_peri_clk_set_parent(struct clk_hw *hw, u8 index)