Re: [PATCH v4 2/2] ACPI / CPPC: Make cppc acpi driver aware of pcc subspace ids
From: George Cherian
Date: Tue Oct 03 2017 - 07:02:03 EST
Hi Prakash,
On 09/29/2017 04:49 AM, Prakash, Prashanth wrote:
Hi George,
On 9/19/2017 11:24 PM, George Cherian wrote:
Based on ACPI 6.2 Section 8.4.7.1.9 If the PCC register space is used,
all PCC registers, for all processors in the same performance
domain (as defined by _PSD), must be defined to be in the same subspace.
Based on Section 14.1 of ACPI specification, it is possible to have a
maximum of 256 PCC subspace ids. Add support of multiple PCC subspace id
instead of using a single global pcc_data structure.
While at that fix the time_delta check in send_pcc_cmd() so that last_mpar_reset
and mpar_count is initialized properly.
Signed-off-by: George Cherian <george.cherian@xxxxxxxxxx>
---
drivers/acpi/cppc_acpi.c | 243 +++++++++++++++++++++++++++++------------------
1 file changed, 153 insertions(+), 90 deletions(-)
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index e5b47f0..3ae79ef 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -75,13 +75,16 @@ struct cppc_pcc_data {
/* Wait queue for CPUs whose requests were batched */
wait_queue_head_t pcc_write_wait_q;
+ ktime_t last_cmd_cmpl_time;
+ ktime_t last_mpar_reset;
+ int mpar_count;
+ int refcount;
};
-/* Structure to represent the single PCC channel */
-static struct cppc_pcc_data pcc_data = {
- .pcc_subspace_idx = -1,
- .platform_owns_pcc = true,
-};
+/* Array to represent the PCC channel per subspace id */
+static struct cppc_pcc_data *pcc_data[MAX_PCC_SUBSPACES];
+/* The cpu_pcc_subspace_idx containsper CPU subspace id */
+static DEFINE_PER_CPU(int, cpu_pcc_subspace_idx);
/*
* The cpc_desc structure contains the ACPI register details
@@ -93,7 +96,8 @@ static struct cppc_pcc_data pcc_data = {
static DEFINE_PER_CPU(struct cpc_desc *, cpc_desc_ptr);
/* pcc mapped address + header size + offset within PCC subspace */
-#define GET_PCC_VADDR(offs) (pcc_data.pcc_comm_addr + 0x8 + (offs))
+#define GET_PCC_VADDR(offs, pcc_ss_id) (pcc_data[pcc_ss_id]->pcc_comm_addr + \
+ 0x8 + (offs))
/* Check if a CPC register is in PCC */
#define CPC_IN_PCC(cpc) ((cpc)->type == ACPI_TYPE_BUFFER && \
@@ -188,13 +192,16 @@ static struct kobj_type cppc_ktype = {
.default_attrs = cppc_attrs,
};
-static int check_pcc_chan(bool chk_err_bit)
+static int check_pcc_chan(int pcc_ss_id, bool chk_err_bit)
{
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);
+ struct cppc_pcc_data *pcc_ss_data = pcc_data[pcc_ss_id];
+ struct acpi_pcct_shared_memory __iomem *generic_comm_base =
+ pcc_ss_data->pcc_comm_addr;
+ ktime_t next_deadline = ktime_add(ktime_get(),
+ pcc_ss_data->deadline);
- if (!pcc_data.platform_owns_pcc)
+ if (!pcc_ss_data->platform_owns_pcc)
return 0;
/* Retry in case the remote processor was too slow to catch up. */
@@ -219,7 +226,7 @@ static int check_pcc_chan(bool chk_err_bit)
}
if (likely(!ret))
- pcc_data.platform_owns_pcc = false;
+ pcc_ss_data->platform_owns_pcc = false;
else
pr_err("PCC check channel failed. Status=%x\n", status);
@@ -230,13 +237,12 @@ static int check_pcc_chan(bool chk_err_bit)
* 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)
+static int send_pcc_cmd(int pcc_ss_id, u16 cmd)
{
int ret = -EIO, i;
+ struct cppc_pcc_data *pcc_ss_data = pcc_data[pcc_ss_id];
struct acpi_pcct_shared_memory *generic_comm_base =
- (struct acpi_pcct_shared_memory *) pcc_data.pcc_comm_addr;
- static ktime_t last_cmd_cmpl_time, last_mpar_reset;
- static int mpar_count;
+ (struct acpi_pcct_shared_memory *)pcc_ss_data->pcc_comm_addr;
unsigned int time_delta;
/*
@@ -249,24 +255,25 @@ static int send_pcc_cmd(u16 cmd)
* before write completion, so first send a WRITE command to
* platform
*/
- if (pcc_data.pending_pcc_write_cmd)
- send_pcc_cmd(CMD_WRITE);
+ if (pcc_ss_data->pending_pcc_write_cmd)
+ send_pcc_cmd(pcc_ss_id, CMD_WRITE);
- ret = check_pcc_chan(false);
+ ret = check_pcc_chan(pcc_ss_id, false);
if (ret)
goto end;
} else /* CMD_WRITE */
- pcc_data.pending_pcc_write_cmd = FALSE;
+ pcc_ss_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_data.pcc_mrtt) {
- time_delta = ktime_us_delta(ktime_get(), last_cmd_cmpl_time);
- if (pcc_data.pcc_mrtt > time_delta)
- udelay(pcc_data.pcc_mrtt - time_delta);
+ if (pcc_ss_data->pcc_mrtt) {
+ time_delta = ktime_us_delta(ktime_get(),
+ pcc_ss_data->last_cmd_cmpl_time);
+ if (pcc_ss_data->pcc_mrtt > time_delta)
+ udelay(pcc_ss_data->pcc_mrtt - time_delta);
}
/*
@@ -280,18 +287,19 @@ static int send_pcc_cmd(u16 cmd)
* not send the request to the platform after hitting the MPAR limit in
* any 60s window
*/
- 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) {
+ if (pcc_ss_data->pcc_mpar) {
+ if (pcc_ss_data->mpar_count == 0) {
+ time_delta = ktime_ms_delta(ktime_get(),
+ pcc_ss_data->last_mpar_reset);
+ if ((time_delta < 60 * MSEC_PER_SEC) && pcc_ss_data->last_mpar_reset) {
pr_debug("PCC cmd not sent due to MPAR limit");
ret = -EIO;
goto end;
}
- last_mpar_reset = ktime_get();
- mpar_count = pcc_data.pcc_mpar;
+ pcc_ss_data->last_mpar_reset = ktime_get();
+ pcc_ss_data->mpar_count = pcc_ss_data->pcc_mpar;
}
- mpar_count--;
+ pcc_ss_data->mpar_count--;
}
/* Write to the shared comm region. */
@@ -300,10 +308,10 @@ static int send_pcc_cmd(u16 cmd)
/* Flip CMD COMPLETE bit */
writew_relaxed(0, &generic_comm_base->status);
- pcc_data.platform_owns_pcc = true;
+ pcc_ss_data->platform_owns_pcc = true;
/* Ring doorbell */
- ret = mbox_send_message(pcc_data.pcc_channel, &cmd);
+ ret = mbox_send_message(pcc_ss_data->pcc_channel, &cmd);
if (ret < 0) {
pr_err("Err sending PCC mbox message. cmd:%d, ret:%d\n",
cmd, ret);
@@ -311,15 +319,15 @@ static int send_pcc_cmd(u16 cmd)
}
/* wait for completion and check for PCC errro bit */
- ret = check_pcc_chan(true);
+ ret = check_pcc_chan(pcc_ss_id, true);
- if (pcc_data.pcc_mrtt)
- last_cmd_cmpl_time = ktime_get();
+ if (pcc_ss_data->pcc_mrtt)
+ pcc_ss_data->last_cmd_cmpl_time = ktime_get();
- if (pcc_data.pcc_channel->mbox->txdone_irq)
- mbox_chan_txdone(pcc_data.pcc_channel, ret);
+ if (pcc_ss_data->pcc_channel->mbox->txdone_irq)
+ mbox_chan_txdone(pcc_ss_data->pcc_channel, ret);
else
- mbox_client_txdone(pcc_data.pcc_channel, ret);
+ mbox_client_txdone(pcc_ss_data->pcc_channel, ret);
end:
if (cmd == CMD_WRITE) {
@@ -329,12 +337,12 @@ static int send_pcc_cmd(u16 cmd)
if (!desc)
continue;
- if (desc->write_cmd_id == pcc_data.pcc_write_cnt)
+ if (desc->write_cmd_id == pcc_ss_data->pcc_write_cnt)
desc->write_cmd_status = ret;
}
}
- pcc_data.pcc_write_cnt++;
- wake_up_all(&pcc_data.pcc_write_wait_q);
+ pcc_ss_data->pcc_write_cnt++;
+ wake_up_all(&pcc_ss_data->pcc_write_wait_q);
}
return ret;
@@ -536,16 +544,16 @@ int acpi_get_psd_map(struct cppc_cpudata **all_cpu_data)
}
EXPORT_SYMBOL_GPL(acpi_get_psd_map);
-static int register_pcc_channel(int pcc_subspace_idx)
+static int register_pcc_channel(int pcc_ss_idx)
{
struct acpi_pcct_hw_reduced *cppc_ss;
u64 usecs_lat;
- if (pcc_subspace_idx >= 0) {
- pcc_data.pcc_channel = pcc_mbox_request_channel(&cppc_mbox_cl,
- pcc_subspace_idx);
+ if (pcc_ss_idx >= 0) {
+ pcc_data[pcc_ss_idx]->pcc_channel =
+ pcc_mbox_request_channel(&cppc_mbox_cl, pcc_ss_idx);
- if (IS_ERR(pcc_data.pcc_channel)) {
+ if (IS_ERR(pcc_data[pcc_ss_idx]->pcc_channel)) {
pr_err("Failed to find PCC communication channel\n");
return -ENODEV;
}
@@ -556,7 +564,7 @@ static int register_pcc_channel(int pcc_subspace_idx)
* PCC channels) and stored pointers to the
* subspace communication region in con_priv.
*/
- cppc_ss = (pcc_data.pcc_channel)->con_priv;
+ cppc_ss = (pcc_data[pcc_ss_idx]->pcc_channel)->con_priv;
if (!cppc_ss) {
pr_err("No PCC subspace found for CPPC\n");
@@ -569,19 +577,20 @@ static int register_pcc_channel(int pcc_subspace_idx)
* So add an arbitrary amount of wait on top of Nominal.
*/
usecs_lat = NUM_RETRIES * cppc_ss->latency;
- 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_data.pcc_comm_addr = acpi_os_ioremap(cppc_ss->base_address, cppc_ss->length);
- if (!pcc_data.pcc_comm_addr) {
+ pcc_data[pcc_ss_idx]->deadline = ns_to_ktime(usecs_lat * NSEC_PER_USEC);
+ pcc_data[pcc_ss_idx]->pcc_mrtt = cppc_ss->min_turnaround_time;
+ pcc_data[pcc_ss_idx]->pcc_mpar = cppc_ss->max_access_rate;
+ pcc_data[pcc_ss_idx]->pcc_nominal = cppc_ss->latency;
+
+ pcc_data[pcc_ss_idx]->pcc_comm_addr =
+ acpi_os_ioremap(cppc_ss->base_address, cppc_ss->length);
+ if (!pcc_data[pcc_ss_idx]->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_data.pcc_channel_acquired = true;
+ pcc_data[pcc_ss_idx]->pcc_channel_acquired = true;
}
return 0;
@@ -600,6 +609,39 @@ bool __weak cpc_ffh_supported(void)
return false;
}
+
+/**
+ * pcc_data_alloc() - Allocate the pcc_data memory for pcc subspace
+ *
+ * Check and allocate the cppc_pcc_data memory.
+ * In some processor configurations it is possible that same subspace
+ * is shared between multiple CPU's. This is seen especially in CPU's
+ * with hardware multi-threading support.
+ *
+ * Return: 0 for success, errno for failure
+ */
+int pcc_data_alloc(int pcc_ss_id)
+{
+ int loop;
+
+ if (pcc_ss_id < 0)
Above should be (pcc_ss_id < 0 || pcc_ss_id >= MAX_PCC_SUBSPACES)
Yes we can have this additional check.
+ return -EINVAL;
+
+ for (loop = 0; pcc_data[loop] != NULL; loop++) {
+ if (pcc_data[loop]->pcc_subspace_idx == pcc_ss_id) {
+ pcc_data[loop]->refcount++;
+ return 0;
+ }
+ }
Why do we need the above for loop? can't it be direct array lookup?
if (pcc_data[pcc_ss_id]) {
ÂÂÂ //increment ref_count and return
}
Yes, we could get rid of the loop and increment the reference directly
if already allocated.
Also, we should remove the pcc_subspace_idx from cppc_pcc_data structure,
it is no longer useful and probably adds to confusion.
Please see below
+
+ pcc_data[pcc_ss_id] = kzalloc(sizeof(struct cppc_pcc_data), GFP_KERNEL);
+ if (!pcc_data[pcc_ss_id])
+ return -ENOMEM;
+ pcc_data[pcc_ss_id]->pcc_subspace_idx = pcc_ss_id;
+ pcc_data[pcc_ss_id]->refcount++;
+
+ return 0;
+}
/*
* An example CPC table looks like the following.
*
@@ -661,6 +703,7 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
struct device *cpu_dev;
acpi_handle handle = pr->handle;
unsigned int num_ent, i, cpc_rev;
+ int pcc_subspace_id = -1;
acpi_status status;
int ret = -EFAULT;
@@ -733,12 +776,9 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
* so extract it only once.
*/
if (gas_t->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
- 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");
We need to retain the above checks to make sure all PCC registers
within a _CPC package is under same subspace. The Spec still requires:
"If the PCC register space is used, all PCC registers, for all processors in
the same performance domain (as defined by _PSD), must be defined
to be in the same subspace."
So that means we need to maintain the pcc_subspace_idx in cppc_pcc_data.
If so, then I can move the check inside pcc_data_alloc().
+ pcc_subspace_id = gas_t->access_width;
+ if (pcc_data_alloc(pcc_subspace_id))
goto out_free;
We need to call pcc_data_alloc(to increment the reference) only once per CPU,
otherwise acpi_cppc_processor_exit( ) will never free the memory allocated in
pcc_data.
It is infact called only once per CPU, The refcounting was added in case
if multiple CPU's share the same domain for eg:
In instances, where CPU have hardware multi-threading support.
or in cases where all CPU's are controlled using single subspace (as
earlier).
Do you see any issue with acpi_cppc_processor_exit() in the earlier
cases, where refcount remains > 0 and the memory not getting freed-up?
--
Thanks,
Prashanth