1 files changed, 39 insertions, 6 deletions

diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
index 1fee1fd87cea..1ee9a3549473 100644
--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -51,6 +51,7 @@
 #define CM_GNRICCTL		0x000
 #define CM_GNRICDIV		0x004
 # define CM_DIV_FRAC_BITS	12
+# define CM_DIV_FRAC_MASK	GENMASK(CM_DIV_FRAC_BITS - 1, 0)
 
 #define CM_VPUCTL		0x008
 #define CM_VPUDIV		0x00c
@@ -128,6 +129,7 @@
 # define CM_GATE			BIT(CM_GATE_BIT)
 # define CM_BUSY			BIT(7)
 # define CM_BUSYD			BIT(8)
+# define CM_FRAC			BIT(9)
 # define CM_SRC_SHIFT			0
 # define CM_SRC_BITS			4
 # define CM_SRC_MASK			0xf
@@ -644,6 +646,7 @@ struct bcm2835_clock_data {
 	u32 frac_bits;
 
 	bool is_vpu_clock;
+	bool is_mash_clock;
 };
 
 static const char *const bcm2835_clock_per_parents[] = {
@@ -825,6 +828,7 @@ static const struct bcm2835_clock_data bcm2835_clock_pwm_data = {
 	.div_reg = CM_PWMDIV,
 	.int_bits = 12,
 	.frac_bits = 12,
+	.is_mash_clock = true,
 };
 
 struct bcm2835_pll {
@@ -1180,7 +1184,7 @@ static u32 bcm2835_clock_choose_div(struct clk_hw *hw,
 		GENMASK(CM_DIV_FRAC_BITS - data->frac_bits, 0) >> 1;
 	u64 temp = (u64)parent_rate << CM_DIV_FRAC_BITS;
 	u64 rem;
-	u32 div;
+	u32 div, mindiv, maxdiv;
 
 	rem = do_div(temp, rate);
 	div = temp;
@@ -1190,11 +1194,23 @@ static u32 bcm2835_clock_choose_div(struct clk_hw *hw,
 		div += unused_frac_mask + 1;
 	div &= ~unused_frac_mask;
 
-	/* clamp to min divider of 1 */
-	div = max_t(u32, div, 1 << CM_DIV_FRAC_BITS);
-	/* clamp to the highest possible fractional divider */
-	div = min_t(u32, div, GENMASK(data->int_bits + CM_DIV_FRAC_BITS - 1,
-				      CM_DIV_FRAC_BITS - data->frac_bits));
+	/* different clamping limits apply for a mash clock */
+	if (data->is_mash_clock) {
+		/* clamp to min divider of 2 */
+		mindiv = 2 << CM_DIV_FRAC_BITS;
+		/* clamp to the highest possible integer divider */
+		maxdiv = (BIT(data->int_bits) - 1) << CM_DIV_FRAC_BITS;
+	} else {
+		/* clamp to min divider of 1 */
+		mindiv = 1 << CM_DIV_FRAC_BITS;
+		/* clamp to the highest possible fractional divider */
+		maxdiv = GENMASK(data->int_bits + CM_DIV_FRAC_BITS - 1,
+				 CM_DIV_FRAC_BITS - data->frac_bits);
+	}
+
+	/* apply the clamping  limits */
+	div = max_t(u32, div, mindiv);
+	div = min_t(u32, div, maxdiv);
 
 	return div;
 }
@@ -1288,9 +1304,26 @@ static int bcm2835_clock_set_rate(struct clk_hw *hw,
 	struct bcm2835_cprman *cprman = clock->cprman;
 	const struct bcm2835_clock_data *data = clock->data;
 	u32 div = bcm2835_clock_choose_div(hw, rate, parent_rate, false);
+	u32 ctl;
+
+	spin_lock(&cprman->regs_lock);
+
+	/*
+	 * Setting up frac support
+	 *
+	 * In principle it is recommended to stop/start the clock first,
+	 * but as we set CLK_SET_RATE_GATE during registration of the
+	 * clock this requirement should be take care of by the
+	 * clk-framework.
+	 */
+	ctl = cprman_read(cprman, data->ctl_reg) & ~CM_FRAC;
+	ctl |= (div & CM_DIV_FRAC_MASK) ? CM_FRAC : 0;
+	cprman_write(cprman, data->ctl_reg, ctl);
 
 	cprman_write(cprman, data->div_reg, div);
 
+	spin_unlock(&cprman->regs_lock);
+
 	return 0;
 }