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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/devicetree/bindings/usb/usb3503.txt b/Documentation/devicetree/bindings/usb/usb3503.txt
index a018da4a7ad7527a5b926b6024362dd03a6f2ce1..221ac0dbc678e70d9a3ba6e24a3b48d2eca35e82 100644 (file)
--- a/Documentation/devicetree/bindings/usb/usb3503.txt
+++ b/Documentation/devicetree/bindings/usb/usb3503.txt
@@ -15,6 +15,14 @@ Optional properties:
 - reset-gpios: Should specify GPIO for reset.
 - initial-mode: Should specify initial mode.
                 (1 for HUB mode, 2 for STANDBY mode)
+- refclk: Clock used for driving REFCLK signal (optional, if not provided
+       the driver assumes that clock signal is always available, its
+       rate is specified by REF_SEL pins and a value from the primary
+       reference clock frequencies table is used)
+- refclk-frequency: Frequency of the REFCLK signal as defined by REF_SEL
+       pins (optional, if not provided, driver will not set rate of the
+       REFCLK signal and assume that a value from the primary reference
+       clock frequencies table is used)
 
 Examples:
        usb3503@08 {

diff --git a/drivers/usb/misc/usb3503.c b/drivers/usb/misc/usb3503.c
index a31641e18d198fa12ffde7b5bbc32cac01ae1d73..f43c61989cef2c1ce64576712162fc79eb62d316 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)
@@ -184,8 +187,58 @@ static int usb3503_probe(struct usb3503 *hub)
                hub->gpio_reset         = pdata->gpio_reset;
                hub->mode               = pdata->initial_mode;
        } else if (np) {
+               struct clk *clk;
                hub->port_off_mask = 0;
 
+               clk = devm_clk_get(dev, "refclk");
+               if (IS_ERR(clk) && PTR_ERR(clk) != -ENOENT) {
+                       dev_err(dev, "unable to request refclk (%d)\n", err);
+                       return PTR_ERR(clk);
+               }
+
+               if (!IS_ERR(clk)) {
+                       u32 rate = 0;
+                       hub->clk = clk;
+
+                       if (!of_property_read_u32(np, "refclk-frequency",
+                                                &rate)) {
+
+                               switch (rate) {
+                               case 38400000:
+                               case 26000000:
+                               case 19200000:
+                               case 12000000:
+                                       hub->secondary_ref_clk = 0;
+                                       break;
+                               case 24000000:
+                               case 27000000:
+                               case 25000000:
+                               case 50000000:
+                                       hub->secondary_ref_clk = 1;
+                                       break;
+                               default:
+                                       dev_err(dev,
+                                               "unsupported reference clock rate (%d)\n",
+                                               (int) rate);
+                                       return -EINVAL;
+                               }
+                               err = clk_set_rate(hub->clk, rate);
+                               if (err) {
+                                       dev_err(dev,
+                                               "unable to set reference clock rate to %d\n",
+                                               (int) rate);
+                                       return err;
+                               }
+                       }
+
+                       err = clk_prepare_enable(hub->clk);
+                       if (err) {
+                               dev_err(dev,
+                                       "unable to enable reference clock\n");
+                               return err;
+                       }
+               }
+
                property = of_get_property(np, "disabled-ports", &len);
                if (property && (len / sizeof(u32)) > 0) {
                        int i;
@@ -213,8 +266,10 @@ 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",