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>

diff --git a/drivers/clk/at91/clk-usb.c b/drivers/clk/at91/clk-usb.c
index 5b3b63c07524390f7addb9adeea90a089193cc13..a23ac0c724f014643e66bc2485f7c79cef523920 100644 (file)
--- 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;