/*
* Copyright (C) 2014 Imagination Technologies
* Author: Paul Burton <paul.burton@imgtec.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*/
#include <linux/init.h>
#include <linux/percpu.h>
#include <linux/slab.h>
#include <asm/asm-offsets.h>
#include <asm/cacheflush.h>
#include <asm/cacheops.h>
#include <asm/idle.h>
#include <asm/mips-cm.h>
#include <asm/mips-cpc.h>
#include <asm/mipsmtregs.h>
#include <asm/pm.h>
#include <asm/pm-cps.h>
#include <asm/smp-cps.h>
#include <asm/uasm.h>
/*
* cps_nc_entry_fn - type of a generated non-coherent state entry function
* @online: the count of online coupled VPEs
* @nc_ready_count: pointer to a non-coherent mapping of the core ready_count
*
* The code entering & exiting non-coherent states is generated at runtime
* using uasm, in order to ensure that the compiler cannot insert a stray
* memory access at an unfortunate time and to allow the generation of optimal
* core-specific code particularly for cache routines. If coupled_coherence
* is non-zero and this is the entry function for the CPS_PM_NC_WAIT state,
* returns the number of VPEs that were in the wait state at the point this
* VPE left it. Returns garbage if coupled_coherence is zero or this is not
* the entry function for CPS_PM_NC_WAIT.
*/
typedef unsigned (*cps_nc_entry_fn)(unsigned online, u32 *nc_ready_count);
/*
* The entry point of the generated non-coherent idle state entry/exit
* functions. Actually per-core rather than per-CPU.
*/
static DEFINE_PER_CPU_READ_MOSTLY(cps_nc_entry_fn[CPS_PM_STATE_COUNT],
nc_asm_enter);
/* Bitmap indicating which states are supported by the system */
DECLARE_BITMAP(state_support, CPS_PM_STATE_COUNT);
/*
* Indicates the number of coupled VPEs ready to operate in a non-coherent
* state. Actually per-core rather than per-CPU.
*/
static DEFINE_PER_CPU_ALIGNED(u32*, ready_count);
static DEFINE_PER_CPU_ALIGNED(void*, ready_count_alloc);
/* Indicates online CPUs coupled with the current CPU */
static DEFINE_PER_CPU_ALIGNED(cpumask_t, online_coupled);
/*
* Used to synchronize entry to deep idle states. Actually per-core rather
* than per-CPU.
*/
static DEFINE_PER_CPU_ALIGNED(atomic_t, pm_barrier);
/* Saved CPU state across the CPS_PM_POWER_GATED state */
DEFINE_PER_CPU_ALIGNED(struct mips_static_suspend_state, cps_cpu_state);
/* A somewhat arbitrary number of labels & relocs for uasm */
static struct uasm_label labels[32] __initdata;
static struct uasm_reloc relocs[32] __initdata;
/* CPU dependant sync types */
static unsigned stype_intervention;
static unsigned stype_memory;
static unsigned stype_ordering;
enum mips_reg {
zero, at, v0, v1, a0, a1, a2, a3,
t0, t1, t2, t3, t4, t5, t6, t7,
s0, s1, s2, s3, s4, s5, s6, s7,
t8, t9, k0, k1, gp, sp, fp, ra,
};
bool cps_pm_support_state(enum cps_pm_state state)
{
return test_bit(state, state_support);
}
static void coupled_barrier(atomic_t *a, unsigned online)
{
/*
* This function is effectively the same as
* cpuidle_coupled_parallel_barrier, which can't be used here since
* there's no cpuidle device.
*/
if (!coupled_coherence)
return;
smp_mb__before_atomic();
atomic_inc(a);
while (atomic_read(a) < online)
cpu_relax();
if (atomic_inc_return(a) == online * 2) {
atomic_set(a, 0);
return;
}
while (atomic_read(a) > online)
cpu_relax();
}
int cps_pm_enter_state(enum cps_pm_state state)
{
unsigned cpu = smp_processor_id();
unsigned core = current_cpu_data.core;
unsigned online, left;
cpumask_t *coupled_mask = this_cpu_ptr(&online_coupled);
u32 *core_ready_count, *nc_core_ready_count;
void *nc_addr;
cps_nc_entry_fn entry;
struct core_boot_config *core_cfg;
struct vpe_boot_config *vpe_cfg;
/* Check that there is an entry function for this state */
entry = per_cpu(nc_asm_enter, core)[state];
if (!entry)
return -EINVAL;
/* Calculate which coupled CPUs (VPEs) are online */
#ifdef CONFIG_MIPS_MT
if (cpu_online(cpu)) {
cpumask_and(coupled_mask, cpu_online_mask,
&cpu_sibling_map[cpu]);
online = cpumask_weight(coupled_mask);
cpumask_clear_cpu(cpu, coupled_mask);
} else
#endif
{
cpumask_clear(coupled_mask);
online = 1;
}
/* Setup the VPE to run mips_cps_pm_restore when started again */
if (config_enabled(CONFIG_CPU_PM) && state == CPS_PM_POWER_GATED) {
/* Power gating relies upon CPS SMP */
if (!mips_cps_smp_in_use())
return -EINVAL;
core_cfg = &mips_cps_core_bootcfg[core];
vpe_cfg = &core_cfg->vpe_config[cpu_vpe_id(¤t_cpu_data)];
vpe_cfg->pc = (unsigned long)mips_cps_pm_restore;
vpe_cfg->gp = (unsigned long)current_thread_info();
vpe_cfg->sp = 0;
}
/* Indicate that this CPU might not be coherent */
cpumask_clear_cpu(cpu, &cpu_coherent_mask);
smp_mb__after_atomic();
/* Create a non-coherent mapping of the core ready_count */
core_ready_count = per_cpu(ready_count, core);
nc_addr = kmap_noncoherent(virt_to_page(core_ready_count),
(unsigned long)core_ready_count);
nc_addr += ((unsigned long)core_ready_count & ~PAGE_MASK);
nc_core_ready_count = nc_addr;
/* Ensure ready_count is zero-initialised before the assembly runs */
ACCESS_ONCE(*nc_core_ready_count) = 0;
coupled_barrier(&per_cpu(pm_barrier, core), online);
/* Run the generated entry code */
left = entry(online, nc_core_ready_count);
/* Remove the non-coherent mapping of ready_count */
kunmap_noncoherent();
/* Indicate that this CPU is definitely coherent */
cpumask_set_cpu(cpu, &cpu_coherent_mask);
/*
* If this VPE is the first to leave the non-coherent wait state then
* it needs to wake up any coupled VPEs still running their wait
* instruction so that they return to cpuidle, which can then complete
* coordination between the coupled VPEs & provide the governor with
* a chance to reflect on the length of time the VPEs were in the
* idle state.
*/
if (coupled_coherence && (state == CPS_PM_NC_WAIT) && (left == online))
arch_send_call_function_ipi_mask(coupled_mask);
return 0;
}
static void __init cps_gen_cache_routine(u32 **pp, struct uasm_label **pl,
struct uasm_reloc **pr,
const struct cache_desc *cache,
unsigned op, int lbl)
{
unsigned cache_size = cache->ways << cache->waybit;
unsigned i;
const unsigned unroll_lines = 32;
/* If the cache isn't present this function has it easy */
if (cache->flags & MIPS_CACHE_NOT_PRESENT)
return;
/* Load base address */
UASM_i_LA(pp, t0, (long)CKSEG0);
/* Calculate end address */
if (cache_size < 0x8000)
uasm_i_addiu(pp, t1, t0, cache_size);
else
UASM_i_LA(pp, t1, (long)(CKSEG0 + cache_size));
/* Start of cache op loop */
uasm_build_label(pl, *pp, lbl);
/* Generate the cache ops */
for (i = 0; i < unroll_lines; i++)
uasm_i_cache(pp, op, i * cache->linesz, t0);
/* Update the base address */
uasm_i_addiu(pp, t0, t0, unroll_lines * cache->linesz);
/* Loop if we haven't reached the end address yet */
uasm_il_bne(pp, pr, t0, t1, lbl);
uasm_i_nop(pp);
}
static int __init cps_gen_flush_fsb(u32 **pp, struct uasm_label **pl,
struct uasm_reloc **pr,
const struct cpuinfo_mips *cpu_info,
int lbl)
{
unsigned i, fsb_size = 8;
unsigned num_loads = (fsb_size * 3) / 2;
unsigned line_stride = 2;
unsigned line_size = cpu_info->dcache.linesz;
unsigned perf_counter, perf_event;
unsigned revision = cpu_info->processor_id & PRID_REV_MASK;
/*
* Determine whether this CPU requires an FSB flush, and if so which
* performance counter/event reflect stalls due to a full FSB.
*/
switch (__get_cpu_type(cpu_info->cputype)) {
case CPU_INTERAPTIV:
perf_counter = 1;
perf_event = 51;
break;
case CPU_PROAPTIV:
/* Newer proAptiv cores don't require this workaround */
if (revision >= PRID_REV_ENCODE_332(1, 1, 0))
return 0;
/* On older ones it's unavailable */
return -1;
/* CPUs which do not require the workaround */
case CPU_P5600:
case CPU_I6400:
return 0;
default:
WARN_ONCE(1, "pm-cps: FSB flush unsupported for this CPU\n");
return -1;
}
/*
* Ensure that the fill/store buffer (FSB) is not holding the results
* of a prefetch, since if it is then the CPC sequencer may become
* stuck in the D3 (ClrBus) state whilst entering a low power state.
*/
/* Preserve perf counter setup */
uasm_i_mfc0(pp, t2, 25, (perf_counter * 2) + 0); /* PerfCtlN */
uasm_i_mfc0(pp, t3, 25, (perf_counter * 2) + 1); /* PerfCntN */
/* Setup perf counter to count FSB full pipeline stalls */
uasm_i_addiu(pp, t0, zero, (perf_event << 5) | 0xf);
uasm_i_mtc0(pp, t0, 25, (perf_counter * 2) + 0); /* PerfCtlN */
uasm_i_ehb(pp);
uasm_i_mtc0(pp, zero, 25, (perf_counter * 2) + 1); /* PerfCntN */
uasm_i_ehb(pp);
/* Base address for loads */
UASM_i_LA(pp, t0, (long)CKSEG0);
/* Start of clear loop */
uasm_build_label(pl, *pp, lbl);
/* Perform some loads to fill the FSB */
for (i = 0; i < num_loads; i++)
uasm_i_lw(pp, zero, i * line_size * line_stride, t0);
/*
* Invalidate the new D-cache entries so that the cache will need
* refilling (via the FSB) if the loop is executed again.
*/
for (i = 0; i < num_loads; i++) {
uasm_i_cache(pp, Hit_Invalidate_D,
i * line_size * line_stride, t0);
uasm_i_cache(pp, Hit_Writeback_Inv_SD,
i * line_size * line_stride, t0);
}
/* Completion barrier */
uasm_i_sync(pp, stype_memory);
uasm_i_ehb(pp);
/* Check whether the pipeline stalled due to the FSB being full */
uasm_i_mfc0(pp, t1, 25, (perf_counter * 2) + 1); /* PerfCntN */
/* Loop if it didn't */
uasm_il_beqz(pp, pr, t1, lbl);
uasm_i_nop(pp);
/* Restore perf counter 1. The count may well now be wrong... */
uasm_i_mtc0(pp, t2, 25, (perf_counter * 2) + 0); /* PerfCtlN */
uasm_i_ehb(pp);
uasm_i_mtc0(pp, t3, 25, (perf_counter * 2) + 1); /* PerfCntN */
uasm_i_ehb(pp);
return 0;
}
static void __init cps_gen_set_top_bit(u32 **pp, struct uasm_label **pl,
struct uasm_reloc **pr,
unsigned r_addr, int lbl)
{
uasm_i_lui(pp, t0, uasm_rel_hi(0x80000000));
uasm_build_label(pl, *pp, lbl);
uasm_i_ll(pp, t1, 0, r_addr);
uasm_i_or(pp, t1, t1, t0);
uasm_i_sc(pp, t1, 0, r_addr);
uasm_il_beqz(pp, pr, t1, lbl);
uasm_i_nop(pp);
}
static void * __init cps_gen_entry_code(unsigned cpu, enum cps_pm_state state)
{
struct uasm_label *l = labels;
struct uasm_reloc *r = relocs;
u32 *buf, *p;
const unsigned r_online = a0;
const unsigned r_nc_count = a1;
const unsigned r_pcohctl = t7;
const unsigned max_instrs = 256;
unsigned cpc_cmd;
int err;
enum {
lbl_incready = 1,
lbl_poll_cont,
lbl_secondary_hang,
lbl_disable_coherence,
lbl_flush_fsb,
lbl_invicache,
lbl_flushdcache,
lbl_hang,
lbl_set_cont,
lbl_secondary_cont,
lbl_decready,
};
/* Allocate a buffer to hold the generated code */
p = buf = kcalloc(max_instrs, sizeof(u32), GFP_KERNEL);
if (!buf)
return NULL;
/* Clear labels & relocs ready for (re)use */
memset(labels, 0, sizeof(labels));
memset(relocs, 0, sizeof(relocs));
if (config_enabled(CONFIG_CPU_PM) && state == CPS_PM_POWER_GATED) {
/* Power gating relies upon CPS SMP */
if (!mips_cps_smp_in_use())
goto out_err;
/*
* Save CPU state. Note the non-standard calling convention
* with the return address placed in v0 to avoid clobbering
* the ra register before it is saved.
*/
UASM_i_LA(&p, t0, (long)mips_cps_pm_save);
uasm_i_jalr(&p, v0, t0);
uasm_i_nop(&p);
}
/*
* Load addresses of required CM & CPC registers. This is done early
* because they're needed in both the enable & disable coherence steps
* but in the coupled case the enable step will only run on one VPE.
*/
UASM_i_LA(&p, r_pcohctl, (long)addr_gcr_cl_coherence());
if (coupled_coherence) {
/* Increment ready_count */
uasm_i_sync(&p, stype_ordering);
uasm_build_label(&l, p, lbl_incready);
uasm_i_ll(&p, t1, 0, r_nc_count);
uasm_i_addiu(&p, t2, t1, 1);
uasm_i_sc(&p, t2, 0, r_nc_count);
uasm_il_beqz(&p, &r, t2, lbl_incready);
uasm_i_addiu(&p, t1, t1, 1);
/* Ordering barrier */
uasm_i_sync(&p, stype_ordering);
/*
* If this is the last VPE to become ready for non-coherence
* then it should branch below.
*/
uasm_il_beq(&p, &r, t1, r_online, lbl_disable_coherence);
uasm_i_nop(&p);
if (state < CPS_PM_POWER_GATED) {
/*
* Otherwise this is not the last VPE to become ready
* for non-coherence. It needs to wait until coherence
* has been disabled before proceeding, which it will do
* by polling for the top bit of ready_count being set.
*/
uasm_i_addiu(&p, t1, zero, -1);
uasm_build_label(&l, p, lbl_poll_cont);
uasm_i_lw(&p, t0, 0, r_nc_count);
uasm_il_bltz(&p, &r, t0, lbl_secondary_cont);
uasm_i_ehb(&p);
uasm_i_yield(&p, zero, t1);
uasm_il_b(&p, &r, lbl_poll_cont);
uasm_i_nop(&p);
} else {
/*
* The core will lose power & this VPE will not continue
* so it can simply halt here.
*/
uasm_i_addiu(&p, t0, zero, TCHALT_H);
uasm_i_mtc0(&p, t0, 2, 4);
uasm_build_label(&l, p, lbl_secondary_hang);
uasm_il_b(&p, &r, lbl_secondary_hang);
uasm_i_nop(&p);
}
}
/*
* This is the point of no return - this VPE will now proceed to
* disable coherence. At this point we *must* be sure that no other
* VPE within the core will interfere with the L1 dcache.
*/
uasm_build_label(&l, p, lbl_disable_coherence);
/* Invalidate the L1 icache */
cps_gen_cache_routine(&p, &l, &r, &cpu_data[cpu].icache,
Index_Invalidate_I, lbl_invicache);
/* Writeback & invalidate the L1 dcache */
cps_gen_cache_routine(&p, &l, &r, &cpu_data[cpu].dcache,
Index_Writeback_Inv_D, lbl_flushdcache);
/* Completion barrier */
uasm_i_sync(&p, stype_memory);
uasm_i_ehb(&p);
/*
* Disable all but self interventions. The load from COHCTL is defined
* by the interAptiv & proAptiv SUMs as ensuring that the operation
* resulting from the preceeding store is complete.
*/
uasm_i_addiu(&p, t0, zero, 1 << cpu_data[cpu].core);
uasm_i_sw(&p, t0, 0, r_pcohctl);
uasm_i_lw(&p, t0, 0, r_pcohctl);
/* Sync to ensure previous interventions are complete */
uasm_i_sync(&p, stype_intervention);
uasm_i_ehb(&p);
/* Disable coherence */
uasm_i_sw(&p, zero, 0, r_pcohctl);
uasm_i_lw(&p, t0, 0, r_pcohctl);
if (state >= CPS_PM_CLOCK_GATED) {
err = cps_gen_flush_fsb(&p, &l, &r, &cpu_data[cpu],
lbl_flush_fsb);
if (err)
goto out_err;
/* Determine the CPC command to issue */
switch (state) {
case CPS_PM_CLOCK_GATED:
cpc_cmd = CPC_Cx_CMD_CLOCKOFF;
break;
case CPS_PM_POWER_GATED:
cpc_cmd = CPC_Cx_CMD_PWRDOWN;
break;
default:
BUG();
goto out_err;
}
/* Issue the CPC command */
UASM_i_LA(&p, t0, (long)addr_cpc_cl_cmd());
uasm_i_addiu(&p, t1, zero, cpc_cmd);
uasm_i_sw(&p, t1, 0, t0);
if (state == CPS_PM_POWER_GATED) {
/* If anything goes wrong just hang */
uasm_build_label(&l, p, lbl_hang);
uasm_il_b(&p, &r, lbl_hang);
uasm_i_nop(&p);
/*
* There's no point generating more code, the core is
* powered down & if powered back up will run from the
* reset vector not from here.
*/
goto gen_done;
}
/* Completion barrier */
uasm_i_sync(&p, stype_memory);
uasm_i_ehb(&p);
}
if (state == CPS_PM_NC_WAIT) {
/*
* At this point it is safe for all VPEs to proceed with
* execution. This VPE will set the top bit of ready_count
* to indicate to the other VPEs that they may continue.
*/
if (coupled_coherence)
cps_gen_set_top_bit(&p, &l, &r, r_nc_count,
lbl_set_cont);
/*
* VPEs which did not disable coherence will continue
* executing, after coherence has been disabled, from this
* point.
*/
uasm_build_label(&l, p, lbl_secondary_cont);
/* Now perform our wait */
uasm_i_wait(&p, 0);
}
/*
* Re-enable coherence. Note that for CPS_PM_NC_WAIT all coupled VPEs
* will run this. The first will actually re-enable coherence & the
* rest will just be performing a rather unusual nop.
*/
uasm_i_addiu(&p, t0, zero, CM_GCR_Cx_COHERENCE_COHDOMAINEN_MSK);
uasm_i_sw(&p, t0, 0, r_pcohctl);
uasm_i_lw(&p, t0, 0, r_pcohctl);
/* Completion barrier */
uasm_i_sync(&p, stype_memory);
uasm_i_ehb(&p);
if (coupled_coherence && (state == CPS_PM_NC_WAIT)) {
/* Decrement ready_count */
uasm_build_label(&l, p, lbl_decready);
uasm_i_sync(&p, stype_ordering);
uasm_i_ll(&p, t1, 0, r_nc_count);
uasm_i_addiu(&p, t2, t1, -1);
uasm_i_sc(&p, t2, 0, r_nc_count);
uasm_il_beqz(&p, &r, t2, lbl_decready);
uasm_i_andi(&p, v0, t1, (1 << fls(smp_num_siblings)) - 1);
/* Ordering barrier */
uasm_i_sync(&p, stype_ordering);
}
if (coupled_coherence && (state == CPS_PM_CLOCK_GATED)) {
/*
* At this point it is safe for all VPEs to proceed with
* execution. This VPE will set the top bit of ready_count
* to indicate to the other VPEs that they may continue.
*/
cps_gen_set_top_bit(&p, &l, &r, r_nc_count, lbl_set_cont);
/*
* This core will be reliant upon another core sending a
* power-up command to the CPC in order to resume operation.
* Thus an arbitrary VPE can't trigger the core leaving the
* idle state and the one that disables coherence might as well
* be the one to re-enable it. The rest will continue from here
* after that has been done.
*/
uasm_build_label(&l, p, lbl_secondary_cont);
/* Ordering barrier */
uasm_i_sync(&p, stype_ordering);
}
/* The core is coherent, time to return to C code */
uasm_i_jr(&p, ra);
uasm_i_nop(&p);
gen_done:
/* Ensure the code didn't exceed the resources allocated for it */
BUG_ON((p - buf) > max_instrs);
BUG_ON((l - labels) > ARRAY_SIZE(labels));
BUG_ON((r - relocs) > ARRAY_SIZE(relocs));
/* Patch branch offsets */
uasm_resolve_relocs(relocs, labels);
/* Flush the icache */
local_flush_icache_range((unsigned long)buf, (unsigned long)p);
return buf;
out_err:
kfree(buf);
return NULL;
}
static int __init cps_gen_core_entries(unsigned cpu)
{
enum cps_pm_state state;
unsigned core = cpu_data[cpu].core;
unsigned dlinesz = cpu_data[cpu].dcache.linesz;
void *entry_fn, *core_rc;
for (state = CPS_PM_NC_WAIT; state < CPS_PM_STATE_COUNT; state++) {
if (per_cpu(nc_asm_enter, core)[state])
continue;
if (!test_bit(state, state_support))
continue;
entry_fn = cps_gen_entry_code(cpu, state);
if (!entry_fn) {
pr_err("Failed to generate core %u state %u entry\n",
core, state);
clear_bit(state, state_support);
}
per_cpu(nc_asm_enter, core)[state] = entry_fn;
}
if (!per_cpu(ready_count, core)) {
core_rc = kmalloc(dlinesz * 2, GFP_KERNEL);
if (!core_rc) {
pr_err("Failed allocate core %u ready_count\n", core);
return -ENOMEM;
}
per_cpu(ready_count_alloc, core) = core_rc;
/* Ensure ready_count is aligned to a cacheline boundary */
core_rc += dlinesz - 1;
core_rc = (void *)((unsigned long)core_rc & ~(dlinesz - 1));
per_cpu(ready_count, core) = core_rc;
}
return 0;
}
static int __init cps_pm_init(void)
{
unsigned cpu;
int err;
/* Detect appropriate sync types for the system */
switch (current_cpu_data.cputype) {
case CPU_INTERAPTIV:
case CPU_PROAPTIV:
case CPU_M5150:
case CPU_P5600:
case CPU_I6400:
stype_intervention = 0x2;
stype_memory = 0x3;
stype_ordering = 0x10;
break;
default:
pr_warn("Power management is using heavyweight sync 0\n");
}
/* A CM is required for all non-coherent states */
if (!mips_cm_present()) {
pr_warn("pm-cps: no CM, non-coherent states unavailable\n");
goto out;
}
/*
* If interrupts were enabled whilst running a wait instruction on a
* non-coherent core then the VPE may end up processing interrupts
* whilst non-coherent. That would be bad.
*/
if (cpu_wait == r4k_wait_irqoff)
set_bit(CPS_PM_NC_WAIT, state_support);
else
pr_warn("pm-cps: non-coherent wait unavailable\n");
/* Detect whether a CPC is present */
if (mips_cpc_present()) {
/* Detect whether clock gating is implemented */
if (read_cpc_cl_stat_conf() & CPC_Cx_STAT_CONF_CLKGAT_IMPL_MSK)
set_bit(CPS_PM_CLOCK_GATED, state_support);
else
pr_warn("pm-cps: CPC does not support clock gating\n");
/* Power gating is available with CPS SMP & any CPC */
if (mips_cps_smp_in_use())
set_bit(CPS_PM_POWER_GATED, state_support);
else
pr_warn("pm-cps: CPS SMP not in use, power gating unavailable\n");
} else {
pr_warn("pm-cps: no CPC, clock & power gating unavailable\n");
}
for_each_present_cpu(cpu) {
err = cps_gen_core_entries(cpu);
if (err)
return err;
}
out:
return 0;
}
arch_initcall(cps_pm_init);