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ACPI / CPPC: restructure read/writes for efficient sys mapped reg ops
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For cases where sys mapped CPC registers need to be accessed
frequently, it helps immensly to pre-map them rather than map
and unmap for each operation. e.g. case where feedback counters
are sys mem map registers.

Restructure cpc_read/write and the cpc_regs structure to allow
pre-mapping the system addresses and unmap them when the CPU exits.

Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
Signed-off-by: Prashanth Prakash <pprakash@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Ashwin Chaugule authored and Rafael J. Wysocki committed Aug 30, 2016
1 parent aca314e commit 5bbb86a
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Showing 2 changed files with 72 additions and 37 deletions.
108 changes: 71 additions & 37 deletions drivers/acpi/cppc_acpi.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,6 @@ static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
/* This layer handles all the PCC specifics for CPPC. */
static struct mbox_chan *pcc_channel;
static void __iomem *pcc_comm_addr;
static u64 comm_base_addr;
static int pcc_subspace_idx = -1;
static bool pcc_channel_acquired;
static ktime_t deadline;
Expand Down Expand Up @@ -394,7 +393,6 @@ EXPORT_SYMBOL_GPL(acpi_get_psd_map);
static int register_pcc_channel(int pcc_subspace_idx)
{
struct acpi_pcct_hw_reduced *cppc_ss;
unsigned int len;
u64 usecs_lat;

if (pcc_subspace_idx >= 0) {
Expand All @@ -419,12 +417,6 @@ static int register_pcc_channel(int pcc_subspace_idx)
return -ENODEV;
}

/*
* This is the shared communication region
* for the OS and Platform to communicate over.
*/
comm_base_addr = cppc_ss->base_address;
len = cppc_ss->length;

/*
* cppc_ss->latency is just a Nominal value. In reality
Expand All @@ -436,7 +428,7 @@ static int register_pcc_channel(int pcc_subspace_idx)
pcc_mrtt = cppc_ss->min_turnaround_time;
pcc_mpar = cppc_ss->max_access_rate;

pcc_comm_addr = acpi_os_ioremap(comm_base_addr, len);
pcc_comm_addr = acpi_os_ioremap(cppc_ss->base_address, cppc_ss->length);
if (!pcc_comm_addr) {
pr_err("Failed to ioremap PCC comm region mem\n");
return -ENOMEM;
Expand Down Expand Up @@ -545,6 +537,8 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
goto out_free;
}

cpc_ptr->num_entries = num_ent;

/* Second entry should be revision. */
cpc_obj = &out_obj->package.elements[1];
if (cpc_obj->type == ACPI_TYPE_INTEGER) {
Expand Down Expand Up @@ -585,7 +579,16 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
pr_debug("Mismatched PCC ids.\n");
goto out_free;
}
} else if (gas_t->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) {
} else if (gas_t->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
if (gas_t->address) {
void __iomem *addr;

addr = ioremap(gas_t->address, gas_t->bit_width/8);
if (!addr)
goto out_free;
cpc_ptr->cpc_regs[i-2].sys_mem_vaddr = addr;
}
} else {
/* Support only PCC and SYS MEM type regs */
pr_debug("Unsupported register type: %d\n", gas_t->space_id);
goto out_free;
Expand Down Expand Up @@ -623,6 +626,13 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
return 0;

out_free:
/* Free all the mapped sys mem areas for this CPU */
for (i = 2; i < cpc_ptr->num_entries; i++) {
void __iomem *addr = cpc_ptr->cpc_regs[i-2].sys_mem_vaddr;

if (addr)
iounmap(addr);
}
kfree(cpc_ptr);

out_buf_free:
Expand All @@ -640,7 +650,17 @@ EXPORT_SYMBOL_GPL(acpi_cppc_processor_probe);
void acpi_cppc_processor_exit(struct acpi_processor *pr)
{
struct cpc_desc *cpc_ptr;
unsigned int i;
void __iomem *addr;
cpc_ptr = per_cpu(cpc_desc_ptr, pr->id);

/* Free all the mapped sys mem areas for this CPU */
for (i = 2; i < cpc_ptr->num_entries; i++) {
addr = cpc_ptr->cpc_regs[i-2].sys_mem_vaddr;
if (addr)
iounmap(addr);
}

kfree(cpc_ptr);
}
EXPORT_SYMBOL_GPL(acpi_cppc_processor_exit);
Expand All @@ -651,15 +671,27 @@ EXPORT_SYMBOL_GPL(acpi_cppc_processor_exit);
* we can directly write to it.
*/

static int cpc_read(struct cpc_reg *reg, u64 *val)
static int cpc_read(struct cpc_register_resource *reg_res, u64 *val)
{
int ret_val = 0;
void __iomem *vaddr = 0;
struct cpc_reg *reg = &reg_res->cpc_entry.reg;

if (reg_res->type == ACPI_TYPE_INTEGER) {
*val = reg_res->cpc_entry.int_value;
return ret_val;
}

*val = 0;
if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
void __iomem *vaddr = GET_PCC_VADDR(reg->address);
if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM)
vaddr = GET_PCC_VADDR(reg->address);
else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
vaddr = reg_res->sys_mem_vaddr;
else
return acpi_os_read_memory((acpi_physical_address)reg->address,
val, reg->bit_width);

switch (reg->bit_width) {
switch (reg->bit_width) {
case 8:
*val = readb_relaxed(vaddr);
break;
Expand All @@ -674,23 +706,28 @@ static int cpc_read(struct cpc_reg *reg, u64 *val)
break;
default:
pr_debug("Error: Cannot read %u bit width from PCC\n",
reg->bit_width);
reg->bit_width);
ret_val = -EFAULT;
}
} else
ret_val = acpi_os_read_memory((acpi_physical_address)reg->address,
val, reg->bit_width);
}

return ret_val;
}

static int cpc_write(struct cpc_reg *reg, u64 val)
static int cpc_write(struct cpc_register_resource *reg_res, u64 val)
{
int ret_val = 0;
void __iomem *vaddr = 0;
struct cpc_reg *reg = &reg_res->cpc_entry.reg;

if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
void __iomem *vaddr = GET_PCC_VADDR(reg->address);
if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM)
vaddr = GET_PCC_VADDR(reg->address);
else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
vaddr = reg_res->sys_mem_vaddr;
else
return acpi_os_write_memory((acpi_physical_address)reg->address,
val, reg->bit_width);

switch (reg->bit_width) {
switch (reg->bit_width) {
case 8:
writeb_relaxed(val, vaddr);
break;
Expand All @@ -705,13 +742,11 @@ static int cpc_write(struct cpc_reg *reg, u64 val)
break;
default:
pr_debug("Error: Cannot write %u bit width to PCC\n",
reg->bit_width);
reg->bit_width);
ret_val = -EFAULT;
break;
}
} else
ret_val = acpi_os_write_memory((acpi_physical_address)reg->address,
val, reg->bit_width);
}

return ret_val;
}

Expand Down Expand Up @@ -754,16 +789,16 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
}
}

cpc_read(&highest_reg->cpc_entry.reg, &high);
cpc_read(highest_reg, &high);
perf_caps->highest_perf = high;

cpc_read(&lowest_reg->cpc_entry.reg, &low);
cpc_read(lowest_reg, &low);
perf_caps->lowest_perf = low;

cpc_read(&ref_perf->cpc_entry.reg, &ref);
cpc_read(ref_perf, &ref);
perf_caps->reference_perf = ref;

cpc_read(&nom_perf->cpc_entry.reg, &nom);
cpc_read(nom_perf, &nom);
perf_caps->nominal_perf = nom;

if (!ref)
Expand Down Expand Up @@ -804,16 +839,16 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)

/* Are any of the regs PCC ?*/
if ((delivered_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) ||
(reference_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM)) {
(reference_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM)) {
/* Ring doorbell once to update PCC subspace */
if (send_pcc_cmd(CMD_READ) < 0) {
ret = -EIO;
goto out_err;
}
}

cpc_read(&delivered_reg->cpc_entry.reg, &delivered);
cpc_read(&reference_reg->cpc_entry.reg, &reference);
cpc_read(delivered_reg, &delivered);
cpc_read(reference_reg, &reference);

if (!delivered || !reference) {
ret = -EFAULT;
Expand Down Expand Up @@ -868,7 +903,7 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
* Skip writing MIN/MAX until Linux knows how to come up with
* useful values.
*/
cpc_write(&desired_reg->cpc_entry.reg, perf_ctrls->desired_perf);
cpc_write(desired_reg, perf_ctrls->desired_perf);

/* Is this a PCC reg ?*/
if (desired_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
Expand All @@ -878,7 +913,6 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
}
busy_channel:
spin_unlock(&pcc_lock);

return ret;
}
EXPORT_SYMBOL_GPL(cppc_set_perf);
1 change: 1 addition & 0 deletions include/acpi/cppc_acpi.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,7 @@ struct cpc_reg {
*/
struct cpc_register_resource {
acpi_object_type type;
u64 __iomem *sys_mem_vaddr;
union {
struct cpc_reg reg;
u64 int_value;
Expand Down

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