[PATCH] ioc4: PCI bus speed detection

Several hardware features of SGI's IOC4 I/O controller chip require
timing-related driver calculations dependent upon the PCI bus speed.  This
patch enables the core IOC4 driver code to detect the actual bus speed and
store a value that can later be used by the IOC4 subdrivers as needed.

Signed-off-by: Brent Casavant <bcasavan@sgi.com>
Acked-by: Pat Gefre <pfg@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 18 insertions, 13 deletions

diff --git a/drivers/serial/ioc4_serial.c b/drivers/serial/ioc4_serial.c
index da5f10eb4845..793c3a7cbe47 100644
--- a/drivers/serial/ioc4_serial.c
+++ b/drivers/serial/ioc4_serial.c
@@ -299,7 +299,6 @@ struct ioc4_serial {
 } ioc4_serial;
 
 /* UART clock speed */
-#define IOC4_SER_XIN_CLK        IOC4_SER_XIN_CLK_66
 #define IOC4_SER_XIN_CLK_66     66666667
 #define IOC4_SER_XIN_CLK_33     33333333
 
@@ -1012,21 +1011,20 @@ static irqreturn_t ioc4_intr(int irq, void *arg, struct pt_regs *regs)
  * ioc4_attach_local - Device initialization.
  *                      Called at *_attach() time for each
  *                      IOC4 with serial ports in the system.
- * @control: ioc4_control ptr
- * @pdev: PCI handle for this device
- * @soft: soft struct for this device
- * @ioc4: ioc4 mem space
+ * @idd: Master module data for this IOC4
  */
-static int inline ioc4_attach_local(struct pci_dev *pdev,
-                        struct ioc4_control *control,
-                        struct ioc4_soft *soft, void __iomem *ioc4_misc,
-                        void __iomem *ioc4_serial)
+static int inline ioc4_attach_local(struct ioc4_driver_data *idd)
 {
         struct ioc4_port *port;
         struct ioc4_port *ports[IOC4_NUM_SERIAL_PORTS];
         int port_number;
         uint16_t ioc4_revid_min = 62;
         uint16_t ioc4_revid;
+        struct pci_dev *pdev = idd->idd_pdev;
+        struct ioc4_control* control = idd->idd_serial_data;
+        struct ioc4_soft *soft = control->ic_soft;
+        void __iomem *ioc4_misc = idd->idd_misc_regs;
+        void __iomem *ioc4_serial = soft->is_ioc4_serial_addr;
 
         /* IOC4 firmware must be at least rev 62 */
         pci_read_config_word(pdev, PCI_COMMAND_SPECIAL, &ioc4_revid);
@@ -1063,7 +1061,15 @@ static int inline ioc4_attach_local(struct pci_dev *pdev,
                 port->ip_ioc4_soft = soft;
                 port->ip_pdev = pdev;
                 port->ip_ienb = 0;
-                port->ip_pci_bus_speed = IOC4_SER_XIN_CLK;
+                /* Use baud rate calculations based on detected PCI
+                 * bus speed.  Simply test whether the PCI clock is
+                 * running closer to 66MHz or 33MHz.
+                 */
+                if (idd->count_period/IOC4_EXTINT_COUNT_DIVISOR < 20) {
+                        port->ip_pci_bus_speed = IOC4_SER_XIN_CLK_66;
+                } else {
+                        port->ip_pci_bus_speed = IOC4_SER_XIN_CLK_33;
+                }
                 port->ip_baud = 9600;
                 port->ip_control = control;
                 port->ip_mem = ioc4_misc;
@@ -2733,9 +2739,8 @@ ioc4_serial_attach_one(struct ioc4_driver_data *idd)
                     "%s : request_irq fails for IRQ 0x%x\n ",
                         __FUNCTION__, idd->idd_pdev->irq);
         }
-        if ((ret = ioc4_attach_local(idd->idd_pdev, control, soft,
-                                soft->is_ioc4_misc_addr,
-                                soft->is_ioc4_serial_addr)))
+        ret = ioc4_attach_local(idd);
+        if (ret)
                 goto out4;
 
         /* register port with the serial core */