in pmac64-cpufreq.c [479:645]
static int __init g5_pm72_cpufreq_init(struct device_node *cpunode)
{
struct device_node *cpuid = NULL, *hwclock = NULL;
const u8 *eeprom = NULL;
const u32 *valp;
u64 max_freq, min_freq, ih, il;
int has_volt = 1, rc = 0;
DBG("cpufreq: Initializing for PowerMac7,2, PowerMac7,3 and"
" RackMac3,1...\n");
/* Lookup the cpuid eeprom node */
cpuid = of_find_node_by_path("/u3@0,f8000000/i2c@f8001000/cpuid@a0");
if (cpuid != NULL)
eeprom = of_get_property(cpuid, "cpuid", NULL);
if (eeprom == NULL) {
pr_err("Can't find cpuid EEPROM !\n");
rc = -ENODEV;
goto bail;
}
/* Lookup the i2c hwclock */
for_each_node_by_name(hwclock, "i2c-hwclock") {
const char *loc = of_get_property(hwclock,
"hwctrl-location", NULL);
if (loc == NULL)
continue;
if (strcmp(loc, "CPU CLOCK"))
continue;
if (!of_get_property(hwclock, "platform-get-frequency", NULL))
continue;
break;
}
if (hwclock == NULL) {
pr_err("Can't find i2c clock chip !\n");
rc = -ENODEV;
goto bail;
}
DBG("cpufreq: i2c clock chip found: %pOF\n", hwclock);
/* Now get all the platform functions */
pfunc_cpu_getfreq =
pmf_find_function(hwclock, "get-frequency");
pfunc_cpu_setfreq_high =
pmf_find_function(hwclock, "set-frequency-high");
pfunc_cpu_setfreq_low =
pmf_find_function(hwclock, "set-frequency-low");
pfunc_slewing_done =
pmf_find_function(hwclock, "slewing-done");
pfunc_cpu0_volt_high =
pmf_find_function(hwclock, "set-voltage-high-0");
pfunc_cpu0_volt_low =
pmf_find_function(hwclock, "set-voltage-low-0");
pfunc_cpu1_volt_high =
pmf_find_function(hwclock, "set-voltage-high-1");
pfunc_cpu1_volt_low =
pmf_find_function(hwclock, "set-voltage-low-1");
/* Check we have minimum requirements */
if (pfunc_cpu_getfreq == NULL || pfunc_cpu_setfreq_high == NULL ||
pfunc_cpu_setfreq_low == NULL || pfunc_slewing_done == NULL) {
pr_err("Can't find platform functions !\n");
rc = -ENODEV;
goto bail;
}
/* Check that we have complete sets */
if (pfunc_cpu0_volt_high == NULL || pfunc_cpu0_volt_low == NULL) {
pmf_put_function(pfunc_cpu0_volt_high);
pmf_put_function(pfunc_cpu0_volt_low);
pfunc_cpu0_volt_high = pfunc_cpu0_volt_low = NULL;
has_volt = 0;
}
if (!has_volt ||
pfunc_cpu1_volt_high == NULL || pfunc_cpu1_volt_low == NULL) {
pmf_put_function(pfunc_cpu1_volt_high);
pmf_put_function(pfunc_cpu1_volt_low);
pfunc_cpu1_volt_high = pfunc_cpu1_volt_low = NULL;
}
/* Note: The device tree also contains a "platform-set-values"
* function for which I haven't quite figured out the usage. It
* might have to be called on init and/or wakeup, I'm not too sure
* but things seem to work fine without it so far ...
*/
/* Get max frequency from device-tree */
valp = of_get_property(cpunode, "clock-frequency", NULL);
if (!valp) {
pr_err("Can't find CPU frequency !\n");
rc = -ENODEV;
goto bail;
}
max_freq = (*valp)/1000;
/* Now calculate reduced frequency by using the cpuid input freq
* ratio. This requires 64 bits math unless we are willing to lose
* some precision
*/
ih = *((u32 *)(eeprom + 0x10));
il = *((u32 *)(eeprom + 0x20));
/* Check for machines with no useful settings */
if (il == ih) {
pr_warn("No low frequency mode available on this model !\n");
rc = -ENODEV;
goto bail;
}
min_freq = 0;
if (ih != 0 && il != 0)
min_freq = (max_freq * il) / ih;
/* Sanity check */
if (min_freq >= max_freq || min_freq < 1000) {
pr_err("Can't calculate low frequency !\n");
rc = -ENXIO;
goto bail;
}
g5_cpu_freqs[0].frequency = max_freq;
g5_cpu_freqs[1].frequency = min_freq;
/* Based on a measurement on Xserve G5, rounded up. */
transition_latency = 10 * NSEC_PER_MSEC;
/* Set callbacks */
g5_switch_volt = g5_pfunc_switch_volt;
g5_switch_freq = g5_pfunc_switch_freq;
g5_query_freq = g5_pfunc_query_freq;
/* Force apply current frequency to make sure everything is in
* sync (voltage is right for example). Firmware may leave us with
* a strange setting ...
*/
g5_switch_volt(CPUFREQ_HIGH);
msleep(10);
g5_pmode_cur = -1;
g5_switch_freq(g5_query_freq());
pr_info("Registering G5 CPU frequency driver\n");
pr_info("Frequency method: i2c/pfunc, Voltage method: %s\n",
has_volt ? "i2c/pfunc" : "none");
pr_info("Low: %d Mhz, High: %d Mhz, Cur: %d MHz\n",
g5_cpu_freqs[1].frequency/1000,
g5_cpu_freqs[0].frequency/1000,
g5_cpu_freqs[g5_pmode_cur].frequency/1000);
rc = cpufreq_register_driver(&g5_cpufreq_driver);
bail:
if (rc != 0) {
pmf_put_function(pfunc_cpu_getfreq);
pmf_put_function(pfunc_cpu_setfreq_high);
pmf_put_function(pfunc_cpu_setfreq_low);
pmf_put_function(pfunc_slewing_done);
pmf_put_function(pfunc_cpu0_volt_high);
pmf_put_function(pfunc_cpu0_volt_low);
pmf_put_function(pfunc_cpu1_volt_high);
pmf_put_function(pfunc_cpu1_volt_low);
}
of_node_put(hwclock);
of_node_put(cpuid);
of_node_put(cpunode);
return rc;
}