#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/ktime.h>
+#include <linux/rwsem.h>
+#include <linux/wait.h>
#include <acpi/cppc_acpi.h>
-/*
- * Lock to provide mutually exclusive access to the PCC
- * channel. e.g. When the remote updates the shared region
- * with new data, the reader needs to be protected from
- * other CPUs activity on the same channel.
- */
-static DEFINE_SPINLOCK(pcc_lock);
+
+struct cppc_pcc_data {
+ struct mbox_chan *pcc_channel;
+ void __iomem *pcc_comm_addr;
+ int pcc_subspace_idx;
+ bool pcc_channel_acquired;
+ ktime_t deadline;
+ unsigned int pcc_mpar, pcc_mrtt, pcc_nominal;
+
+ bool pending_pcc_write_cmd; /* Any pending/batched PCC write cmds? */
+ bool platform_owns_pcc; /* Ownership of PCC subspace */
+ unsigned int pcc_write_cnt; /* Running count of PCC write commands */
+
+ /*
+ * Lock to provide controlled access to the PCC channel.
+ *
+ * For performance critical usecases(currently cppc_set_perf)
+ * We need to take read_lock and check if channel belongs to OSPM
+ * before reading or writing to PCC subspace
+ * We need to take write_lock before transferring the channel
+ * ownership to the platform via a Doorbell
+ * This allows us to batch a number of CPPC requests if they happen
+ * to originate in about the same time
+ *
+ * For non-performance critical usecases(init)
+ * Take write_lock for all purposes which gives exclusive access
+ */
+ struct rw_semaphore pcc_lock;
+
+ /* Wait queue for CPUs whose requests were batched */
+ wait_queue_head_t pcc_write_wait_q;
+};
+
+/* Structure to represent the single PCC channel */
+static struct cppc_pcc_data pcc_data = {
+ .pcc_subspace_idx = -1,
+ .platform_owns_pcc = true,
+};
/*
* The cpc_desc structure contains the ACPI register details
*/
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;
-static unsigned int pcc_mpar, pcc_mrtt;
-
/* pcc mapped address + header size + offset within PCC subspace */
-#define GET_PCC_VADDR(offs) (pcc_comm_addr + 0x8 + (offs))
-
+#define GET_PCC_VADDR(offs) (pcc_data.pcc_comm_addr + 0x8 + (offs))
+
+/* Check if a CPC regsiter is in PCC */
+#define CPC_IN_PCC(cpc) ((cpc)->type == ACPI_TYPE_BUFFER && \
+ (cpc)->cpc_entry.reg.space_id == \
+ ACPI_ADR_SPACE_PLATFORM_COMM)
+
+/* Evalutes to True if reg is a NULL register descriptor */
+#define IS_NULL_REG(reg) ((reg)->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY && \
+ (reg)->address == 0 && \
+ (reg)->bit_width == 0 && \
+ (reg)->bit_offset == 0 && \
+ (reg)->access_width == 0)
+
+/* Evalutes to True if an optional cpc field is supported */
+#define CPC_SUPPORTED(cpc) ((cpc)->type == ACPI_TYPE_INTEGER ? \
+ !!(cpc)->cpc_entry.int_value : \
+ !IS_NULL_REG(&(cpc)->cpc_entry.reg))
/*
* Arbitrary Retries in case the remote processor is slow to respond
* to PCC commands. Keeping it high enough to cover emulators where
*/
#define NUM_RETRIES 500
-static int check_pcc_chan(void)
+struct cppc_attr {
+ struct attribute attr;
+ ssize_t (*show)(struct kobject *kobj,
+ struct attribute *attr, char *buf);
+ ssize_t (*store)(struct kobject *kobj,
+ struct attribute *attr, const char *c, ssize_t count);
+};
+
+#define define_one_cppc_ro(_name) \
+static struct cppc_attr _name = \
+__ATTR(_name, 0444, show_##_name, NULL)
+
+#define to_cpc_desc(a) container_of(a, struct cpc_desc, kobj)
+
+static ssize_t show_feedback_ctrs(struct kobject *kobj,
+ struct attribute *attr, char *buf)
+{
+ struct cpc_desc *cpc_ptr = to_cpc_desc(kobj);
+ struct cppc_perf_fb_ctrs fb_ctrs = {0};
+
+ cppc_get_perf_ctrs(cpc_ptr->cpu_id, &fb_ctrs);
+
+ return scnprintf(buf, PAGE_SIZE, "ref:%llu del:%llu\n",
+ fb_ctrs.reference, fb_ctrs.delivered);
+}
+define_one_cppc_ro(feedback_ctrs);
+
+static ssize_t show_reference_perf(struct kobject *kobj,
+ struct attribute *attr, char *buf)
+{
+ struct cpc_desc *cpc_ptr = to_cpc_desc(kobj);
+ struct cppc_perf_fb_ctrs fb_ctrs = {0};
+
+ cppc_get_perf_ctrs(cpc_ptr->cpu_id, &fb_ctrs);
+
+ return scnprintf(buf, PAGE_SIZE, "%llu\n",
+ fb_ctrs.reference_perf);
+}
+define_one_cppc_ro(reference_perf);
+
+static ssize_t show_wraparound_time(struct kobject *kobj,
+ struct attribute *attr, char *buf)
+{
+ struct cpc_desc *cpc_ptr = to_cpc_desc(kobj);
+ struct cppc_perf_fb_ctrs fb_ctrs = {0};
+
+ cppc_get_perf_ctrs(cpc_ptr->cpu_id, &fb_ctrs);
+
+ return scnprintf(buf, PAGE_SIZE, "%llu\n", fb_ctrs.ctr_wrap_time);
+
+}
+define_one_cppc_ro(wraparound_time);
+
+static struct attribute *cppc_attrs[] = {
+ &feedback_ctrs.attr,
+ &reference_perf.attr,
+ &wraparound_time.attr,
+ NULL
+};
+
+static struct kobj_type cppc_ktype = {
+ .sysfs_ops = &kobj_sysfs_ops,
+ .default_attrs = cppc_attrs,
+};
+
+static int check_pcc_chan(bool chk_err_bit)
{
- int ret = -EIO;
- struct acpi_pcct_shared_memory __iomem *generic_comm_base = pcc_comm_addr;
- ktime_t next_deadline = ktime_add(ktime_get(), deadline);
+ int ret = -EIO, status = 0;
+ struct acpi_pcct_shared_memory __iomem *generic_comm_base = pcc_data.pcc_comm_addr;
+ ktime_t next_deadline = ktime_add(ktime_get(), pcc_data.deadline);
+
+ if (!pcc_data.platform_owns_pcc)
+ return 0;
/* Retry in case the remote processor was too slow to catch up. */
while (!ktime_after(ktime_get(), next_deadline)) {
* platform and should have set the command completion bit when
* PCC can be used by OSPM
*/
- if (readw_relaxed(&generic_comm_base->status) & PCC_CMD_COMPLETE) {
+ status = readw_relaxed(&generic_comm_base->status);
+ if (status & PCC_CMD_COMPLETE_MASK) {
ret = 0;
+ if (chk_err_bit && (status & PCC_ERROR_MASK))
+ ret = -EIO;
break;
}
/*
udelay(3);
}
+ if (likely(!ret))
+ pcc_data.platform_owns_pcc = false;
+ else
+ pr_err("PCC check channel failed. Status=%x\n", status);
+
return ret;
}
+/*
+ * This function transfers the ownership of the PCC to the platform
+ * So it must be called while holding write_lock(pcc_lock)
+ */
static int send_pcc_cmd(u16 cmd)
{
- int ret = -EIO;
+ int ret = -EIO, i;
struct acpi_pcct_shared_memory *generic_comm_base =
- (struct acpi_pcct_shared_memory *) pcc_comm_addr;
+ (struct acpi_pcct_shared_memory *) pcc_data.pcc_comm_addr;
static ktime_t last_cmd_cmpl_time, last_mpar_reset;
static int mpar_count;
unsigned int time_delta;
* the channel before writing to PCC space
*/
if (cmd == CMD_READ) {
- ret = check_pcc_chan();
+ /*
+ * If there are pending cpc_writes, then we stole the channel
+ * before write completion, so first send a WRITE command to
+ * platform
+ */
+ if (pcc_data.pending_pcc_write_cmd)
+ send_pcc_cmd(CMD_WRITE);
+
+ ret = check_pcc_chan(false);
if (ret)
- return ret;
- }
+ goto end;
+ } else /* CMD_WRITE */
+ pcc_data.pending_pcc_write_cmd = FALSE;
/*
* Handle the Minimum Request Turnaround Time(MRTT)
* "The minimum amount of time that OSPM must wait after the completion
* of a command before issuing the next command, in microseconds"
*/
- if (pcc_mrtt) {
+ if (pcc_data.pcc_mrtt) {
time_delta = ktime_us_delta(ktime_get(), last_cmd_cmpl_time);
- if (pcc_mrtt > time_delta)
- udelay(pcc_mrtt - time_delta);
+ if (pcc_data.pcc_mrtt > time_delta)
+ udelay(pcc_data.pcc_mrtt - time_delta);
}
/*
* not send the request to the platform after hitting the MPAR limit in
* any 60s window
*/
- if (pcc_mpar) {
+ if (pcc_data.pcc_mpar) {
if (mpar_count == 0) {
time_delta = ktime_ms_delta(ktime_get(), last_mpar_reset);
if (time_delta < 60 * MSEC_PER_SEC) {
pr_debug("PCC cmd not sent due to MPAR limit");
- return -EIO;
+ ret = -EIO;
+ goto end;
}
last_mpar_reset = ktime_get();
- mpar_count = pcc_mpar;
+ mpar_count = pcc_data.pcc_mpar;
}
mpar_count--;
}
/* Flip CMD COMPLETE bit */
writew_relaxed(0, &generic_comm_base->status);
+ pcc_data.platform_owns_pcc = true;
+
/* Ring doorbell */
- ret = mbox_send_message(pcc_channel, &cmd);
+ ret = mbox_send_message(pcc_data.pcc_channel, &cmd);
if (ret < 0) {
pr_err("Err sending PCC mbox message. cmd:%d, ret:%d\n",
cmd, ret);
- return ret;
+ goto end;
}
- /*
- * For READs we need to ensure the cmd completed to ensure
- * the ensuing read()s can proceed. For WRITEs we dont care
- * because the actual write()s are done before coming here
- * and the next READ or WRITE will check if the channel
- * is busy/free at the entry of this call.
- *
- * If Minimum Request Turnaround Time is non-zero, we need
- * to record the completion time of both READ and WRITE
- * command for proper handling of MRTT, so we need to check
- * for pcc_mrtt in addition to CMD_READ
- */
- if (cmd == CMD_READ || pcc_mrtt) {
- ret = check_pcc_chan();
- if (pcc_mrtt)
- last_cmd_cmpl_time = ktime_get();
+ /* wait for completion and check for PCC errro bit */
+ ret = check_pcc_chan(true);
+
+ if (pcc_data.pcc_mrtt)
+ last_cmd_cmpl_time = ktime_get();
+
+ mbox_client_txdone(pcc_data.pcc_channel, ret);
+
+end:
+ if (cmd == CMD_WRITE) {
+ if (unlikely(ret)) {
+ for_each_possible_cpu(i) {
+ struct cpc_desc *desc = per_cpu(cpc_desc_ptr, i);
+ if (!desc)
+ continue;
+
+ if (desc->write_cmd_id == pcc_data.pcc_write_cnt)
+ desc->write_cmd_status = ret;
+ }
+ }
+ pcc_data.pcc_write_cnt++;
+ wake_up_all(&pcc_data.pcc_write_wait_q);
}
- mbox_client_txdone(pcc_channel, ret);
return ret;
}
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) {
- pcc_channel = pcc_mbox_request_channel(&cppc_mbox_cl,
+ pcc_data.pcc_channel = pcc_mbox_request_channel(&cppc_mbox_cl,
pcc_subspace_idx);
- if (IS_ERR(pcc_channel)) {
+ if (IS_ERR(pcc_data.pcc_channel)) {
pr_err("Failed to find PCC communication channel\n");
return -ENODEV;
}
* PCC channels) and stored pointers to the
* subspace communication region in con_priv.
*/
- cppc_ss = pcc_channel->con_priv;
+ cppc_ss = (pcc_data.pcc_channel)->con_priv;
if (!cppc_ss) {
pr_err("No PCC subspace found for CPPC\n");
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
* the remote processor could be much slower to reply.
* So add an arbitrary amount of wait on top of Nominal.
*/
usecs_lat = NUM_RETRIES * cppc_ss->latency;
- deadline = ns_to_ktime(usecs_lat * NSEC_PER_USEC);
- pcc_mrtt = cppc_ss->min_turnaround_time;
- pcc_mpar = cppc_ss->max_access_rate;
+ pcc_data.deadline = ns_to_ktime(usecs_lat * NSEC_PER_USEC);
+ pcc_data.pcc_mrtt = cppc_ss->min_turnaround_time;
+ pcc_data.pcc_mpar = cppc_ss->max_access_rate;
+ pcc_data.pcc_nominal = cppc_ss->latency;
- pcc_comm_addr = acpi_os_ioremap(comm_base_addr, len);
- if (!pcc_comm_addr) {
+ pcc_data.pcc_comm_addr = acpi_os_ioremap(cppc_ss->base_address, cppc_ss->length);
+ if (!pcc_data.pcc_comm_addr) {
pr_err("Failed to ioremap PCC comm region mem\n");
return -ENOMEM;
}
/* Set flag so that we dont come here for each CPU. */
- pcc_channel_acquired = true;
+ pcc_data.pcc_channel_acquired = true;
}
return 0;
}
+/**
+ * cpc_ffh_supported() - check if FFH reading supported
+ *
+ * Check if the architecture has support for functional fixed hardware
+ * read/write capability.
+ *
+ * Return: true for supported, false for not supported
+ */
+bool __weak cpc_ffh_supported(void)
+{
+ return false;
+}
+
/*
* An example CPC table looks like the following.
*
union acpi_object *out_obj, *cpc_obj;
struct cpc_desc *cpc_ptr;
struct cpc_reg *gas_t;
+ struct device *cpu_dev;
acpi_handle handle = pr->handle;
unsigned int num_ent, i, cpc_rev;
acpi_status status;
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) {
* so extract it only once.
*/
if (gas_t->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
- if (pcc_subspace_idx < 0)
- pcc_subspace_idx = gas_t->access_width;
- else if (pcc_subspace_idx != gas_t->access_width) {
+ if (pcc_data.pcc_subspace_idx < 0)
+ pcc_data.pcc_subspace_idx = gas_t->access_width;
+ else if (pcc_data.pcc_subspace_idx != gas_t->access_width) {
pr_debug("Mismatched PCC ids.\n");
goto out_free;
}
- } else if (gas_t->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) {
- /* Support only PCC and SYS MEM type regs */
- pr_debug("Unsupported register type: %d\n", gas_t->space_id);
- goto out_free;
+ } 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 {
+ if (gas_t->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE || !cpc_ffh_supported()) {
+ /* Support only PCC ,SYS MEM and FFH type regs */
+ pr_debug("Unsupported register type: %d\n", gas_t->space_id);
+ goto out_free;
+ }
}
cpc_ptr->cpc_regs[i-2].type = ACPI_TYPE_BUFFER;
goto out_free;
/* Register PCC channel once for all CPUs. */
- if (!pcc_channel_acquired) {
- ret = register_pcc_channel(pcc_subspace_idx);
+ if (!pcc_data.pcc_channel_acquired) {
+ ret = register_pcc_channel(pcc_data.pcc_subspace_idx);
if (ret)
goto out_free;
+
+ init_rwsem(&pcc_data.pcc_lock);
+ init_waitqueue_head(&pcc_data.pcc_write_wait_q);
}
/* Plug PSD data into this CPUs CPC descriptor. */
/* Everything looks okay */
pr_debug("Parsed CPC struct for CPU: %d\n", pr->id);
+ /* Add per logical CPU nodes for reading its feedback counters. */
+ cpu_dev = get_cpu_device(pr->id);
+ if (!cpu_dev)
+ goto out_free;
+
+ ret = kobject_init_and_add(&cpc_ptr->kobj, &cppc_ktype, &cpu_dev->kobj,
+ "acpi_cppc");
+ if (ret)
+ goto out_free;
+
kfree(output.pointer);
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:
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);
+ }
+
+ kobject_put(&cpc_ptr->kobj);
kfree(cpc_ptr);
}
EXPORT_SYMBOL_GPL(acpi_cppc_processor_exit);
+/**
+ * cpc_read_ffh() - Read FFH register
+ * @cpunum: cpu number to read
+ * @reg: cppc register information
+ * @val: place holder for return value
+ *
+ * Read bit_width bits from a specified address and bit_offset
+ *
+ * Return: 0 for success and error code
+ */
+int __weak cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
+{
+ return -ENOTSUPP;
+}
+
+/**
+ * cpc_write_ffh() - Write FFH register
+ * @cpunum: cpu number to write
+ * @reg: cppc register information
+ * @val: value to write
+ *
+ * Write value of bit_width bits to a specified address and bit_offset
+ *
+ * Return: 0 for success and error code
+ */
+int __weak cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
+{
+ return -ENOTSUPP;
+}
+
/*
* Since cpc_read and cpc_write are called while holding pcc_lock, it should be
* as fast as possible. We have already mapped the PCC subspace during init, so
* we can directly write to it.
*/
-static int cpc_read(struct cpc_reg *reg, u64 *val)
+static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
{
int ret_val = 0;
+ void __iomem *vaddr = 0;
+ struct cpc_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 if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
+ return cpc_read_ffh(cpu, reg, val);
+ 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;
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(int cpu, struct cpc_register_resource *reg_res, u64 val)
{
int ret_val = 0;
+ void __iomem *vaddr = 0;
+ struct cpc_reg *reg = ®_res->cpc_entry.reg;
+
+ 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 if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE)
+ return cpc_write_ffh(cpu, reg, val);
+ else
+ return acpi_os_write_memory((acpi_physical_address)reg->address,
+ val, reg->bit_width);
- if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
- void __iomem *vaddr = GET_PCC_VADDR(reg->address);
-
- switch (reg->bit_width) {
+ switch (reg->bit_width) {
case 8:
writeb_relaxed(val, vaddr);
break;
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;
}
struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
struct cpc_register_resource *highest_reg, *lowest_reg, *ref_perf,
*nom_perf;
- u64 high, low, ref, nom;
- int ret = 0;
+ u64 high, low, nom;
+ int ret = 0, regs_in_pcc = 0;
if (!cpc_desc) {
pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
ref_perf = &cpc_desc->cpc_regs[REFERENCE_PERF];
nom_perf = &cpc_desc->cpc_regs[NOMINAL_PERF];
- spin_lock(&pcc_lock);
-
/* Are any of the regs PCC ?*/
- if ((highest_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) ||
- (lowest_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) ||
- (ref_perf->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) ||
- (nom_perf->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM)) {
+ if (CPC_IN_PCC(highest_reg) || CPC_IN_PCC(lowest_reg) ||
+ CPC_IN_PCC(ref_perf) || CPC_IN_PCC(nom_perf)) {
+ regs_in_pcc = 1;
+ down_write(&pcc_data.pcc_lock);
/* Ring doorbell once to update PCC subspace */
if (send_pcc_cmd(CMD_READ) < 0) {
ret = -EIO;
}
}
- cpc_read(&highest_reg->cpc_entry.reg, &high);
+ cpc_read(cpunum, highest_reg, &high);
perf_caps->highest_perf = high;
- cpc_read(&lowest_reg->cpc_entry.reg, &low);
+ cpc_read(cpunum, lowest_reg, &low);
perf_caps->lowest_perf = low;
- cpc_read(&ref_perf->cpc_entry.reg, &ref);
- perf_caps->reference_perf = ref;
-
- cpc_read(&nom_perf->cpc_entry.reg, &nom);
+ cpc_read(cpunum, nom_perf, &nom);
perf_caps->nominal_perf = nom;
- if (!ref)
- perf_caps->reference_perf = perf_caps->nominal_perf;
-
if (!high || !low || !nom)
ret = -EFAULT;
out_err:
- spin_unlock(&pcc_lock);
+ if (regs_in_pcc)
+ up_write(&pcc_data.pcc_lock);
return ret;
}
EXPORT_SYMBOL_GPL(cppc_get_perf_caps);
int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
{
struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
- struct cpc_register_resource *delivered_reg, *reference_reg;
- u64 delivered, reference;
- int ret = 0;
+ struct cpc_register_resource *delivered_reg, *reference_reg,
+ *ref_perf_reg, *ctr_wrap_reg;
+ u64 delivered, reference, ref_perf, ctr_wrap_time;
+ int ret = 0, regs_in_pcc = 0;
if (!cpc_desc) {
pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
delivered_reg = &cpc_desc->cpc_regs[DELIVERED_CTR];
reference_reg = &cpc_desc->cpc_regs[REFERENCE_CTR];
+ ref_perf_reg = &cpc_desc->cpc_regs[REFERENCE_PERF];
+ ctr_wrap_reg = &cpc_desc->cpc_regs[CTR_WRAP_TIME];
- spin_lock(&pcc_lock);
+ /*
+ * If refernce perf register is not supported then we should
+ * use the nominal perf value
+ */
+ if (!CPC_SUPPORTED(ref_perf_reg))
+ ref_perf_reg = &cpc_desc->cpc_regs[NOMINAL_PERF];
/* 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)) {
+ if (CPC_IN_PCC(delivered_reg) || CPC_IN_PCC(reference_reg) ||
+ CPC_IN_PCC(ctr_wrap_reg) || CPC_IN_PCC(ref_perf_reg)) {
+ down_write(&pcc_data.pcc_lock);
+ regs_in_pcc = 1;
/* Ring doorbell once to update PCC subspace */
if (send_pcc_cmd(CMD_READ) < 0) {
ret = -EIO;
}
}
- cpc_read(&delivered_reg->cpc_entry.reg, &delivered);
- cpc_read(&reference_reg->cpc_entry.reg, &reference);
+ cpc_read(cpunum, delivered_reg, &delivered);
+ cpc_read(cpunum, reference_reg, &reference);
+ cpc_read(cpunum, ref_perf_reg, &ref_perf);
- if (!delivered || !reference) {
+ /*
+ * Per spec, if ctr_wrap_time optional register is unsupported, then the
+ * performance counters are assumed to never wrap during the lifetime of
+ * platform
+ */
+ ctr_wrap_time = (u64)(~((u64)0));
+ if (CPC_SUPPORTED(ctr_wrap_reg))
+ cpc_read(cpunum, ctr_wrap_reg, &ctr_wrap_time);
+
+ if (!delivered || !reference || !ref_perf) {
ret = -EFAULT;
goto out_err;
}
perf_fb_ctrs->delivered = delivered;
perf_fb_ctrs->reference = reference;
-
- perf_fb_ctrs->delivered -= perf_fb_ctrs->prev_delivered;
- perf_fb_ctrs->reference -= perf_fb_ctrs->prev_reference;
-
- perf_fb_ctrs->prev_delivered = delivered;
- perf_fb_ctrs->prev_reference = reference;
-
+ perf_fb_ctrs->reference_perf = ref_perf;
+ perf_fb_ctrs->ctr_wrap_time = ctr_wrap_time;
out_err:
- spin_unlock(&pcc_lock);
+ if (regs_in_pcc)
+ up_write(&pcc_data.pcc_lock);
return ret;
}
EXPORT_SYMBOL_GPL(cppc_get_perf_ctrs);
desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
- spin_lock(&pcc_lock);
-
- /* If this is PCC reg, check if channel is free before writing */
- if (desired_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
- ret = check_pcc_chan();
- if (ret)
- goto busy_channel;
+ /*
+ * This is Phase-I where we want to write to CPC registers
+ * -> We want all CPUs to be able to execute this phase in parallel
+ *
+ * Since read_lock can be acquired by multiple CPUs simultaneously we
+ * achieve that goal here
+ */
+ if (CPC_IN_PCC(desired_reg)) {
+ down_read(&pcc_data.pcc_lock); /* BEGIN Phase-I */
+ if (pcc_data.platform_owns_pcc) {
+ ret = check_pcc_chan(false);
+ if (ret) {
+ up_read(&pcc_data.pcc_lock);
+ return ret;
+ }
+ }
+ /*
+ * Update the pending_write to make sure a PCC CMD_READ will not
+ * arrive and steal the channel during the switch to write lock
+ */
+ pcc_data.pending_pcc_write_cmd = true;
+ cpc_desc->write_cmd_id = pcc_data.pcc_write_cnt;
+ cpc_desc->write_cmd_status = 0;
}
/*
* 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(cpu, desired_reg, perf_ctrls->desired_perf);
- /* Is this a PCC reg ?*/
- if (desired_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
- /* Ring doorbell so Remote can get our perf request. */
- if (send_pcc_cmd(CMD_WRITE) < 0)
- ret = -EIO;
+ if (CPC_IN_PCC(desired_reg))
+ up_read(&pcc_data.pcc_lock); /* END Phase-I */
+ /*
+ * This is Phase-II where we transfer the ownership of PCC to Platform
+ *
+ * Short Summary: Basically if we think of a group of cppc_set_perf
+ * requests that happened in short overlapping interval. The last CPU to
+ * come out of Phase-I will enter Phase-II and ring the doorbell.
+ *
+ * We have the following requirements for Phase-II:
+ * 1. We want to execute Phase-II only when there are no CPUs
+ * currently executing in Phase-I
+ * 2. Once we start Phase-II we want to avoid all other CPUs from
+ * entering Phase-I.
+ * 3. We want only one CPU among all those who went through Phase-I
+ * to run phase-II
+ *
+ * If write_trylock fails to get the lock and doesn't transfer the
+ * PCC ownership to the platform, then one of the following will be TRUE
+ * 1. There is at-least one CPU in Phase-I which will later execute
+ * write_trylock, so the CPUs in Phase-I will be responsible for
+ * executing the Phase-II.
+ * 2. Some other CPU has beaten this CPU to successfully execute the
+ * write_trylock and has already acquired the write_lock. We know for a
+ * fact it(other CPU acquiring the write_lock) couldn't have happened
+ * before this CPU's Phase-I as we held the read_lock.
+ * 3. Some other CPU executing pcc CMD_READ has stolen the
+ * down_write, in which case, send_pcc_cmd will check for pending
+ * CMD_WRITE commands by checking the pending_pcc_write_cmd.
+ * So this CPU can be certain that its request will be delivered
+ * So in all cases, this CPU knows that its request will be delivered
+ * by another CPU and can return
+ *
+ * After getting the down_write we still need to check for
+ * pending_pcc_write_cmd to take care of the following scenario
+ * The thread running this code could be scheduled out between
+ * Phase-I and Phase-II. Before it is scheduled back on, another CPU
+ * could have delivered the request to Platform by triggering the
+ * doorbell and transferred the ownership of PCC to platform. So this
+ * avoids triggering an unnecessary doorbell and more importantly before
+ * triggering the doorbell it makes sure that the PCC channel ownership
+ * is still with OSPM.
+ * pending_pcc_write_cmd can also be cleared by a different CPU, if
+ * there was a pcc CMD_READ waiting on down_write and it steals the lock
+ * before the pcc CMD_WRITE is completed. pcc_send_cmd checks for this
+ * case during a CMD_READ and if there are pending writes it delivers
+ * the write command before servicing the read command
+ */
+ if (CPC_IN_PCC(desired_reg)) {
+ if (down_write_trylock(&pcc_data.pcc_lock)) { /* BEGIN Phase-II */
+ /* Update only if there are pending write commands */
+ if (pcc_data.pending_pcc_write_cmd)
+ send_pcc_cmd(CMD_WRITE);
+ up_write(&pcc_data.pcc_lock); /* END Phase-II */
+ } else
+ /* Wait until pcc_write_cnt is updated by send_pcc_cmd */
+ wait_event(pcc_data.pcc_write_wait_q,
+ cpc_desc->write_cmd_id != pcc_data.pcc_write_cnt);
+
+ /* send_pcc_cmd updates the status in case of failure */
+ ret = cpc_desc->write_cmd_status;
}
-busy_channel:
- spin_unlock(&pcc_lock);
-
return ret;
}
EXPORT_SYMBOL_GPL(cppc_set_perf);
+
+/**
+ * cppc_get_transition_latency - returns frequency transition latency in ns
+ *
+ * ACPI CPPC does not explicitly specifiy how a platform can specify the
+ * transition latency for perfromance change requests. The closest we have
+ * is the timing information from the PCCT tables which provides the info
+ * on the number and frequency of PCC commands the platform can handle.
+ */
+unsigned int cppc_get_transition_latency(int cpu_num)
+{
+ /*
+ * Expected transition latency is based on the PCCT timing values
+ * Below are definition from ACPI spec:
+ * pcc_nominal- Expected latency to process a command, in microseconds
+ * pcc_mpar - The maximum number of periodic requests that the subspace
+ * channel can support, reported in commands per minute. 0
+ * indicates no limitation.
+ * pcc_mrtt - The minimum amount of time that OSPM must wait after the
+ * completion of a command before issuing the next command,
+ * in microseconds.
+ */
+ unsigned int latency_ns = 0;
+ struct cpc_desc *cpc_desc;
+ struct cpc_register_resource *desired_reg;
+
+ cpc_desc = per_cpu(cpc_desc_ptr, cpu_num);
+ if (!cpc_desc)
+ return CPUFREQ_ETERNAL;
+
+ desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
+ if (!CPC_IN_PCC(desired_reg))
+ return CPUFREQ_ETERNAL;
+
+ if (pcc_data.pcc_mpar)
+ latency_ns = 60 * (1000 * 1000 * 1000 / pcc_data.pcc_mpar);
+
+ latency_ns = max(latency_ns, pcc_data.pcc_nominal * 1000);
+ latency_ns = max(latency_ns, pcc_data.pcc_mrtt * 1000);
+
+ return latency_ns;
+}
+EXPORT_SYMBOL_GPL(cppc_get_transition_latency);
projects / cascardo / linux.git / blobdiff