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port_enable and port_reset must change atomically. 

I have observed two separate EHCI host bridges that do not tolerate
using C bit-fields to directly manipulate the portsc_t register.  The
reason for this is that the EHCI spec says that port_enable must go
to 0 at the time that port_reset goes to 1.  Naturally this cannot be
done using direct bit-field manipulation.  Instead, we use a temporary
variable, change the bit-fields there, then atomically write the new
value back to the hardware.

Signed-off-by: Steven A. Falco <sfalco@coincident.com>
Change-Id: If138faee43e0293efa203b86f7893fdf1e811269
Reviewed-on: http://review.coreboot.org/101
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
This commit is contained in:
Steven A. Falco 2011-07-15 21:44:35 -04:00 committed by Patrick Georgi
parent 43358a5e24
commit 4c514aedd8
1 changed files with 32 additions and 7 deletions
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39
payloads/libpayload/drivers/usb/ehci_rh.c
View File

@ -54,14 +54,19 @@ static void
ehci_rh_hand_over_port (usbdev_t *dev, int port)
{
volatile portsc_t *p = &(RH_INST(dev)->ports[port]);
volatile portsc_t tmp;
printf("giving up port %x, it's USB1\n", port+1);
/* Lowspeed device. Hand over to companion */
p->port_owner = 1;
tmp = *p;
tmp.port_owner = 1;
*p = tmp;
do {} while (!p->conn_status_change);
/* RW/C register, so clear it by writing 1 */
p->conn_status_change = 1;
tmp = *p;
tmp.conn_status_change = 1;
*p = tmp;
return;
}
@ -69,6 +74,7 @@ static void
ehci_rh_scanport (usbdev_t *dev, int port)
{
volatile portsc_t *p = &(RH_INST(dev)->ports[port]);
volatile portsc_t tmp;
if (RH_INST(dev)->devices[port]!=-1) {
printf("Unregister device at port %x\n", port+1);
usb_detach_device(dev->controller, RH_INST(dev)->devices[port]);
@ -81,10 +87,22 @@ ehci_rh_scanport (usbdev_t *dev, int port)
ehci_rh_hand_over_port(dev, port);
return;
}
p->port_enable = 0;
p->port_reset = 1;
/* Deassert enable, assert reset. These must change
* atomically.
*/
tmp = *p;
tmp.port_enable = 0;
tmp.port_reset = 1;
*p = tmp;
/* Wait a bit while reset is active. */
mdelay(50);
p->port_reset = 0;
/* Deassert reset. */
tmp.port_reset = 0;
*p = tmp;
/* Wait for flag change to finish. The controller might take a while */
while (p->port_reset) ;
if (!p->port_enable) {
@ -95,7 +113,9 @@ ehci_rh_scanport (usbdev_t *dev, int port)
RH_INST(dev)->devices[port] = usb_attach_device(dev->controller, dev->address, port, 2);
}
/* RW/C register, so clear it by writing 1 */
p->conn_status_change = 1;
tmp = *p;
tmp.conn_status_change = 1;
*p = tmp;
}
static int
@ -122,6 +142,8 @@ void
ehci_rh_init (usbdev_t *dev)
{
int i;
volatile portsc_t *p;
volatile portsc_t tmp;
dev->destroy = ehci_rh_destroy;
dev->poll = ehci_rh_poll;
@ -135,8 +157,11 @@ ehci_rh_init (usbdev_t *dev)
RH_INST(dev)->devices = malloc(RH_INST(dev)->n_ports * sizeof(int));
for (i=0; i < RH_INST(dev)->n_ports; i++) {
p = &(RH_INST(dev)->ports[i]);
RH_INST(dev)->devices[i] = -1;
RH_INST(dev)->ports[i].pp = 1;
tmp = *p;
tmp.pp = 1;
*p = tmp;
}
dev->address = 0;