usb: usb5303: add support for reference clock specified in device tree

USB3503 chip supports 8 values of reference clock. The value is
specified by REF_SEL[1:0] pins and INT_N line. This patch add support
for getting 'refclk' clock, enabling it and setting INT_N line according
to the value of the gathered clock. If no clock has been specified,
driver defaults to the old behaviour (assuming that clock has been
specified by REF_SEL pins from primary reference clock frequencies
table).

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Change-Id: I3453e714f9a793640b8cb6c0b4ccf699661ec934

diff --git a/drivers/usb/misc/usb3503.c b/drivers/usb/misc/usb3503.c
index a31641e..52cb754 100644 (file)
--- a/drivers/usb/misc/usb3503.c
+++ b/drivers/usb/misc/usb3503.c
@@ -18,6 +18,7 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
+#include <linux/clk.h>
 #include <linux/i2c.h>
 #include <linux/gpio.h>
 #include <linux/delay.h>
@@ -57,10 +58,12 @@ struct usb3503 {
        enum usb3503_mode       mode;
        struct regmap           *regmap;
        struct device           *dev;
+       struct clk              *clk;
        u8      port_off_mask;
        int     gpio_intn;
        int     gpio_reset;
        int     gpio_connect;
+       bool    secondary_ref_clk;
 };
 
 static int usb3503_reset(struct usb3503 *hub, int state)
@@ -186,6 +189,25 @@ static int usb3503_probe(struct usb3503 *hub)
        } else if (np) {
                hub->port_off_mask = 0;
 
+               hub->clk = devm_clk_get(dev, "refclk");
+               if (!IS_ERR(hub->clk)) {
+                       unsigned long rate;
+
+                       clk_prepare_enable(hub->clk);
+                       rate = clk_get_rate(hub->clk);
+
+                       if (rate == 38400000 || rate == 26000000 ||
+                           rate == 19200000 || rate == 12000000)
+                               hub->secondary_ref_clk = 0;
+                       else if (rate == 24000000 || rate == 27000000 ||
+                           rate == 25000000 || rate == 50000000)
+                               hub->secondary_ref_clk = 1;
+                       else
+                               dev_err(dev,
+                                       "unsupported reference clock rate (%d)\n",
+                                       rate);
+               }
+
                property = of_get_property(np, "disabled-ports", &len);
                if (property && (len / sizeof(u32)) > 0) {
                        int i;
@@ -213,8 +235,10 @@ static int usb3503_probe(struct usb3503 *hub)
                dev_err(dev, "Ports disabled with no control interface\n");
 
        if (gpio_is_valid(hub->gpio_intn)) {
-               err = devm_gpio_request_one(dev, hub->gpio_intn,
-                               GPIOF_OUT_INIT_HIGH, "usb3503 intn");
+               int val = hub->secondary_ref_clk ? GPIOF_OUT_INIT_LOW :
+                                                  GPIOF_OUT_INIT_HIGH;
+               err = devm_gpio_request_one(dev, hub->gpio_intn, val,
+                                           "usb3503 intn");
                if (err) {
                        dev_err(dev,
                                "unable to request GPIO %d as connect pin (%d)\n",