Author: imp
Date: Thu Feb 21 00:27:51 2013
New Revision: 247066
URL: http://svnweb.freebsd.org/changeset/base/247066
Log:
Replace splhigh() with critical_enter()/leave() to ensure we write the
config mode unlock sequence quickly enough. This likely isn't too critical,
since splhigh() has been a noop for a decade...
Modified:
head/sys/dev/ppc/ppc.c
Modified: head/sys/dev/ppc/ppc.c
==============================================================================
--- head/sys/dev/ppc/ppc.c Thu Feb 21 00:26:31 2013 (r247065)
+++ head/sys/dev/ppc/ppc.c Thu Feb 21 00:27:51 2013 (r247066)
@@ -74,6 +74,22 @@ static void ppcintr(void *arg);
#define DEVTOSOFTC(dev) ((struct ppc_data *)device_get_softc(dev))
+/*
+ * We use critical enter/leave for the simple config locking needed to
+ * detect the devices. We just want to make sure that both of our writes
+ * happen without someone else also writing to those config registers. Since
+ * we just do this at startup, Giant keeps multiple threads from executing,
+ * and critical_enter() then is all that's needed to keep us from being
preempted
+ * during the critical sequences with the hardware.
+ *
+ * Note: this doesn't prevent multiple threads from putting the chips into
+ * config mode, but since we only do that to detect the type at startup the
+ * extra overhead isn't needed since Giant protects us from multiple entry
+ * and no other code changes these registers.
+ */
+#define PPC_CONFIG_LOCK(ppc) critical_enter()
+#define PPC_CONFIG_UNLOCK(ppc) critical_leave()
+
devclass_t ppc_devclass;
const char ppc_driver_name[] = "ppc";
@@ -689,7 +705,7 @@ ppc_pc873xx_detect(struct ppc_data *ppc,
static int
ppc_smc37c66xgt_detect(struct ppc_data *ppc, int chipset_mode)
{
- int s, i;
+ int i;
u_char r;
int type = -1;
int csr = SMC66x_CSR; /* initial value is 0x3F0 */
@@ -702,11 +718,10 @@ ppc_smc37c66xgt_detect(struct ppc_data *
/*
* Detection: enter configuration mode and read CRD register.
*/
-
- s = splhigh();
+ PPC_CONFIG_LOCK(ppc);
outb(csr, SMC665_iCODE);
outb(csr, SMC665_iCODE);
- splx(s);
+ PPC_CONFIG_UNLOCK(ppc);
outb(csr, 0xd);
if (inb(cio) == 0x65) {
@@ -715,10 +730,10 @@ ppc_smc37c66xgt_detect(struct ppc_data *
}
for (i = 0; i < 2; i++) {
- s = splhigh();
+ PPC_CONFIG_LOCK(ppc);
outb(csr, SMC666_iCODE);
outb(csr, SMC666_iCODE);
- splx(s);
+ PPC_CONFIG_UNLOCK(ppc);
outb(csr, 0xd);
if (inb(cio) == 0x66) {
@@ -734,16 +749,20 @@ config:
/*
* If chipset not found, do not continue.
*/
- if (type == -1)
+ if (type == -1) {
+ outb(csr, 0xaa); /* end config mode */
return (-1);
+ }
/* select CR1 */
outb(csr, 0x1);
/* read the port's address: bits 0 and 1 of CR1 */
r = inb(cio) & SMC_CR1_ADDR;
- if (port_address[(int)r] != ppc->ppc_base)
+ if (port_address[(int)r] != ppc->ppc_base) {
+ outb(csr, 0xaa); /* end config mode */
return (-1);
+ }
ppc->ppc_model = type;
@@ -881,8 +900,7 @@ end_detect:
outb(cio, (r | SMC_CR4_EPPTYPE));
}
- /* end config mode */
- outb(csr, 0xaa);
+ outb(csr, 0xaa); /* end config mode */
ppc->ppc_type = PPC_TYPE_SMCLIKE;
ppc_smclike_setmode(ppc, chipset_mode);
@@ -897,13 +915,12 @@ end_detect:
static int
ppc_smc37c935_detect(struct ppc_data *ppc, int chipset_mode)
{
- int s;
int type = -1;
- s = splhigh();
+ PPC_CONFIG_LOCK(ppc);
outb(SMC935_CFG, 0x55); /* enter config mode */
outb(SMC935_CFG, 0x55);
- splx(s);
+ PPC_CONFIG_UNLOCK(ppc);
outb(SMC935_IND, SMC935_ID); /* check device id */
if (inb(SMC935_DAT) == 0x2)
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