linux-kernel - [PATCH 06/19] clk: at91: sam9x60-pll: check fcore against ranges

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Date:   Wed, 15 Jul 2020 14:24:14 +0300
From:   Claudiu Beznea <claudiu.beznea@...rochip.com>
To:     <mturquette@...libre.com>, <sboyd@...nel.org>,
        <nicolas.ferre@...rochip.com>, <alexandre.belloni@...tlin.com>,
        <ludovic.desroches@...rochip.com>
CC:     <bbrezillon@...nel.org>, <linux-kernel@...r.kernel.org>,
        <linux-clk@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        "Claudiu Beznea" <claudiu.beznea@...rochip.com>
Subject: [PATCH 06/19] clk: at91: sam9x60-pll: check fcore against ranges

According to datasheet the range of 600-1200MHz is for the the
frequency generated by the fractional part of the PLL (namely
Fcorepllck according to datasheet). With this in mind the output
range of the PLL itself (fractional + div), taking into account
that the diverder is 8 bits wide, is 600/256-1200Hz=2.3-1200MHz.

Fixes: a436c2a447e59 ("clk: at91: add sam9x60 PLL driver")
Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
---
 drivers/clk/at91/clk-sam9x60-pll.c | 12 +++++++++++-
 drivers/clk/at91/sam9x60.c         |  2 +-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/at91/clk-sam9x60-pll.c b/drivers/clk/at91/clk-sam9x60-pll.c
index dfb91c190bd1..00f2afd6e9b6 100644
--- a/drivers/clk/at91/clk-sam9x60-pll.c
+++ b/drivers/clk/at91/clk-sam9x60-pll.c
@@ -21,6 +21,9 @@
 #define UPLL_DIV		2
 #define PLL_MUL_MAX		(FIELD_GET(PMC_PLL_CTRL1_MUL_MSK, UINT_MAX) + 1)
 
+#define FCORE_MIN		(600000000)
+#define FCORE_MAX		(1200000000)
+
 #define PLL_MAX_ID		1
 
 struct sam9x60_pll {
@@ -169,6 +172,7 @@ static long sam9x60_pll_get_best_div_mul(struct sam9x60_pll *pll,
 	unsigned long bestdiv = 0;
 	unsigned long bestmul = 0;
 	unsigned long bestfrac = 0;
+	unsigned long long fcore = 0;
 
 	if (rate < characteristics->output[0].min ||
 	    rate > characteristics->output[0].max)
@@ -213,6 +217,11 @@ static long sam9x60_pll_get_best_div_mul(struct sam9x60_pll *pll,
 				remainder = rate - tmprate;
 		}
 
+		fcore = parent_rate * (tmpmul + 1) +
+			((u64)parent_rate * tmpfrac >> 22);
+		if (fcore < FCORE_MIN || fcore > FCORE_MAX)
+			continue;
+
 		/*
 		 * Compare the remainder with the best remainder found until
 		 * now and elect a new best multiplier/divider pair if the
@@ -232,7 +241,8 @@ static long sam9x60_pll_get_best_div_mul(struct sam9x60_pll *pll,
 	}
 
 	/* Check if bestrate is a valid output rate  */
-	if (bestrate < characteristics->output[0].min ||
+	if (fcore < FCORE_MIN || fcore > FCORE_MAX ||
+	    bestrate < characteristics->output[0].min ||
 	    bestrate > characteristics->output[0].max)
 		return -ERANGE;
 
diff --git a/drivers/clk/at91/sam9x60.c b/drivers/clk/at91/sam9x60.c
index 3e20aa68259f..633891b98d43 100644
--- a/drivers/clk/at91/sam9x60.c
+++ b/drivers/clk/at91/sam9x60.c
@@ -22,7 +22,7 @@ static const struct clk_master_layout sam9x60_master_layout = {
 };
 
 static const struct clk_range plla_outputs[] = {
-	{ .min = 300000000, .max = 600000000 },
+	{ .min = 2343750, .max = 1200000000 },
 };
 
 static const struct clk_pll_characteristics plla_characteristics = {
-- 
2.7.4