clk: at91: usb: fix at91sam9x5 recalc, round and set rate

First check for rate == 0 in set_rate and round_rate to avoid div by zero.
Then, in order to get the closest rate, round all divisions to the closest
result instead of rounding them down.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Michael Turquette <mturquette@linaro.org>

1 files changed, 15 insertions, 14 deletions

diff --git a/drivers/clk/at91/clk-usb.c b/drivers/clk/at91/clk-usb.c
index 5b3b63c07524..a23ac0c724f0 100644
--- a/drivers/clk/at91/clk-usb.c
+++ b/drivers/clk/at91/clk-usb.c
@@ -52,29 +52,26 @@ static unsigned long at91sam9x5_clk_usb_recalc_rate(struct clk_hw *hw,
 
         tmp = pmc_read(pmc, AT91_PMC_USB);
         usbdiv = (tmp & AT91_PMC_OHCIUSBDIV) >> SAM9X5_USB_DIV_SHIFT;
-        return parent_rate / (usbdiv + 1);
+
+        return DIV_ROUND_CLOSEST(parent_rate, (usbdiv + 1));
 }
 
 static long at91sam9x5_clk_usb_round_rate(struct clk_hw *hw, unsigned long rate,
                                           unsigned long *parent_rate)
 {
         unsigned long div;
-        unsigned long bestrate;
-        unsigned long tmp;
+
+        if (!rate)
+                return -EINVAL;
 
         if (rate >= *parent_rate)
                 return *parent_rate;
 
-        div = *parent_rate / rate;
-        if (div >= SAM9X5_USB_MAX_DIV)
-                return *parent_rate / (SAM9X5_USB_MAX_DIV + 1);
-
-        bestrate = *parent_rate / div;
-        tmp = *parent_rate / (div + 1);
-        if (bestrate - rate > rate - tmp)
-                bestrate = tmp;
+        div = DIV_ROUND_CLOSEST(*parent_rate, rate);
+        if (div > SAM9X5_USB_MAX_DIV + 1)
+                div = SAM9X5_USB_MAX_DIV + 1;
 
-        return bestrate;
+        return DIV_ROUND_CLOSEST(*parent_rate, div);
 }
 
 static int at91sam9x5_clk_usb_set_parent(struct clk_hw *hw, u8 index)
@@ -106,9 +103,13 @@ static int at91sam9x5_clk_usb_set_rate(struct clk_hw *hw, unsigned long rate,
         u32 tmp;
         struct at91sam9x5_clk_usb *usb = to_at91sam9x5_clk_usb(hw);
         struct at91_pmc *pmc = usb->pmc;
-        unsigned long div = parent_rate / rate;
+        unsigned long div;
 
-        if (parent_rate % rate || div < 1 || div >= SAM9X5_USB_MAX_DIV)
+        if (!rate)
+                return -EINVAL;
+
+        div = DIV_ROUND_CLOSEST(parent_rate, rate);
+        if (div > SAM9X5_USB_MAX_DIV + 1 || !div)
                 return -EINVAL;
 
         tmp = pmc_read(pmc, AT91_PMC_USB) & ~AT91_PMC_OHCIUSBDIV;