diff options
Diffstat (limited to 'drivers/macintosh/windfarm_pid.c')
| -rw-r--r-- | drivers/macintosh/windfarm_pid.c | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/drivers/macintosh/windfarm_pid.c b/drivers/macintosh/windfarm_pid.c new file mode 100644 index 000000000..f10efb28c --- /dev/null +++ b/drivers/macintosh/windfarm_pid.c @@ -0,0 +1,149 @@ +/* + * Windfarm PowerMac thermal control. Generic PID helpers + * + * (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp. + * <benh@kernel.crashing.org> + * + * Released under the term of the GNU GPL v2. + */ + +#include <linux/types.h> +#include <linux/errno.h> +#include <linux/kernel.h> +#include <linux/string.h> +#include <linux/module.h> + +#include "windfarm_pid.h" + +#undef DEBUG + +#ifdef DEBUG +#define DBG(args...) printk(args) +#else +#define DBG(args...) do { } while(0) +#endif + +void wf_pid_init(struct wf_pid_state *st, struct wf_pid_param *param) +{ + memset(st, 0, sizeof(struct wf_pid_state)); + st->param = *param; + st->first = 1; +} +EXPORT_SYMBOL_GPL(wf_pid_init); + +s32 wf_pid_run(struct wf_pid_state *st, s32 new_sample) +{ + s64 error, integ, deriv; + s32 target; + int i, hlen = st->param.history_len; + + /* Calculate error term */ + error = new_sample - st->param.itarget; + + /* Get samples into our history buffer */ + if (st->first) { + for (i = 0; i < hlen; i++) { + st->samples[i] = new_sample; + st->errors[i] = error; + } + st->first = 0; + st->index = 0; + } else { + st->index = (st->index + 1) % hlen; + st->samples[st->index] = new_sample; + st->errors[st->index] = error; + } + + /* Calculate integral term */ + for (i = 0, integ = 0; i < hlen; i++) + integ += st->errors[(st->index + hlen - i) % hlen]; + integ *= st->param.interval; + + /* Calculate derivative term */ + deriv = st->errors[st->index] - + st->errors[(st->index + hlen - 1) % hlen]; + deriv /= st->param.interval; + + /* Calculate target */ + target = (s32)((integ * (s64)st->param.gr + deriv * (s64)st->param.gd + + error * (s64)st->param.gp) >> 36); + if (st->param.additive) + target += st->target; + target = max(target, st->param.min); + target = min(target, st->param.max); + st->target = target; + + return st->target; +} +EXPORT_SYMBOL_GPL(wf_pid_run); + +void wf_cpu_pid_init(struct wf_cpu_pid_state *st, + struct wf_cpu_pid_param *param) +{ + memset(st, 0, sizeof(struct wf_cpu_pid_state)); + st->param = *param; + st->first = 1; +} +EXPORT_SYMBOL_GPL(wf_cpu_pid_init); + +s32 wf_cpu_pid_run(struct wf_cpu_pid_state *st, s32 new_power, s32 new_temp) +{ + s64 integ, deriv, prop; + s32 error, target, sval, adj; + int i, hlen = st->param.history_len; + + /* Calculate error term */ + error = st->param.pmaxadj - new_power; + + /* Get samples into our history buffer */ + if (st->first) { + for (i = 0; i < hlen; i++) { + st->powers[i] = new_power; + st->errors[i] = error; + } + st->temps[0] = st->temps[1] = new_temp; + st->first = 0; + st->index = st->tindex = 0; + } else { + st->index = (st->index + 1) % hlen; + st->powers[st->index] = new_power; + st->errors[st->index] = error; + st->tindex = (st->tindex + 1) % 2; + st->temps[st->tindex] = new_temp; + } + + /* Calculate integral term */ + for (i = 0, integ = 0; i < hlen; i++) + integ += st->errors[(st->index + hlen - i) % hlen]; + integ *= st->param.interval; + integ *= st->param.gr; + sval = st->param.tmax - (s32)(integ >> 20); + adj = min(st->param.ttarget, sval); + + DBG("integ: %lx, sval: %lx, adj: %lx\n", integ, sval, adj); + + /* Calculate derivative term */ + deriv = st->temps[st->tindex] - + st->temps[(st->tindex + 2 - 1) % 2]; + deriv /= st->param.interval; + deriv *= st->param.gd; + + /* Calculate proportional term */ + prop = st->last_delta = (new_temp - adj); + prop *= st->param.gp; + + DBG("deriv: %lx, prop: %lx\n", deriv, prop); + + /* Calculate target */ + target = st->target + (s32)((deriv + prop) >> 36); + target = max(target, st->param.min); + target = min(target, st->param.max); + st->target = target; + + return st->target; +} +EXPORT_SYMBOL_GPL(wf_cpu_pid_run); + +MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>"); +MODULE_DESCRIPTION("PID algorithm for PowerMacs thermal control"); +MODULE_LICENSE("GPL"); |