Re: [PATCH v3 1/4] ACPI: CPPC: Add cppc_get_reg_val and cppc_set_reg_val function
From: Pierre Gondois
Date: Tue Dec 17 2024 - 08:48:43 EST
Hello Lifeng,
On 12/16/24 10:16, Lifeng Zheng wrote:
Rename cppc_get_perf() to cppc_get_reg_val() as a generic function to read
cppc registers, with four changes:
1. Change the error kind to "no such device" when pcc_ss_id < 0, which
means that this cpu cannot get a valid pcc_ss_id.
2. Add a check to verify if the register is a cpc supported one before
using it.
3. Extract the operations if register is in pcc out as
cppc_get_reg_val_in_pcc().
4. Return the result of cpc_read() instead of 0.
Add cppc_set_reg_val_in_pcc() and cppc_set_reg_val() as generic functions
for setting cppc registers value. Unlike other set reg ABIs,
cppc_set_reg_val() checks CPC_SUPPORTED right after getting the register,
because the rest of the operations are meaningless if this register is not
a cpc supported one.
These functions can be used to reduce some existing code duplication.
Signed-off-by: Lifeng Zheng <zhenglifeng1@xxxxxxxxxx>
---
drivers/acpi/cppc_acpi.c | 111 +++++++++++++++++++++++++++++----------
1 file changed, 84 insertions(+), 27 deletions(-)
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index c1f3568d0c50..bb5333a503a2 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -1179,43 +1179,100 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
return ret_val;
}
-static int cppc_get_perf(int cpunum, enum cppc_regs reg_idx, u64 *perf)
+static int cppc_get_reg_val_in_pcc(int cpu, struct cpc_register_resource *reg, u64 *val)
{
- struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
+ int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
+ struct cppc_pcc_data *pcc_ss_data = NULL;
+ int ret;
+
+ if (pcc_ss_id < 0) {
+ pr_debug("Invalid pcc_ss_id\n");
+ return -ENODEV;
+ }
+
+ pcc_ss_data = pcc_data[pcc_ss_id];
+
+ down_write(&pcc_ss_data->pcc_lock);
+
+ if (send_pcc_cmd(pcc_ss_id, CMD_READ) >= 0)
+ ret = cpc_read(cpu, reg, val);
+ else
+ ret = -EIO;
+
+ up_write(&pcc_ss_data->pcc_lock);
+
+ return ret;
+}
+
+static int cppc_get_reg_val(int cpu, enum cppc_regs reg_idx, u64 *val)
+{
+ struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
struct cpc_register_resource *reg;
if (!cpc_desc) {
- pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
+ pr_debug("No CPC descriptor for CPU:%d\n", cpu);
return -ENODEV;
}
reg = &cpc_desc->cpc_regs[reg_idx];
- if (CPC_IN_PCC(reg)) {
- int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
- struct cppc_pcc_data *pcc_ss_data = NULL;
- int ret = 0;
-
- if (pcc_ss_id < 0)
- return -EIO;
+ if (!CPC_SUPPORTED(reg)) {
+ pr_debug("CPC register (reg_idx=%d) is not supported\n", reg_idx);
+ return -EOPNOTSUPP;
+ }
I think this is only valid for optional fields. Meaning that:
- if the function is used one day for the mandatory 'Lowest Performance'
field, an integer value of 0 would be valid.
- if the function is used for a mandatory field containing a NULL Buffer,
it seems we would return -EFAULT currently, through cpc_read(). -EOPNOTSUPP
doesn't seem appropriate as the field would be mandatory.
Maybe the function needs an additional 'bool optional' input parameter
to do these check conditionally.
- pcc_ss_data = pcc_data[pcc_ss_id];
+ if (CPC_IN_PCC(reg))
+ return cppc_get_reg_val_in_pcc(cpu, reg, val);
- down_write(&pcc_ss_data->pcc_lock);
+ return cpc_read(cpu, reg, val);
+}
- if (send_pcc_cmd(pcc_ss_id, CMD_READ) >= 0)
- cpc_read(cpunum, reg, perf);
- else
- ret = -EIO;
+static int cppc_set_reg_val_in_pcc(int cpu, struct cpc_register_resource *reg, u64 val)
+{
+ int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
+ struct cppc_pcc_data *pcc_ss_data = NULL;
+ int ret;
- up_write(&pcc_ss_data->pcc_lock);
+ if (pcc_ss_id < 0) {
+ pr_debug("Invalid pcc_ss_id\n");
+ return -ENODEV;
+ }
+ ret = cpc_write(cpu, reg, val);
+ if (ret)
return ret;
+
+ pcc_ss_data = pcc_data[pcc_ss_id];
+
+ down_write(&pcc_ss_data->pcc_lock);
+ /* after writing CPC, transfer the ownership of PCC to platform */
+ ret = send_pcc_cmd(pcc_ss_id, CMD_WRITE);
+ up_write(&pcc_ss_data->pcc_lock);
+
+ return ret;
+}
+
+static int cppc_set_reg_val(int cpu, enum cppc_regs reg_idx, u64 val)
+{
+ struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
+ struct cpc_register_resource *reg;
+
+ if (!cpc_desc) {
+ pr_debug("No CPC descriptor for CPU:%d\n", cpu);
+ return -ENODEV;
}
- cpc_read(cpunum, reg, perf);
+ reg = &cpc_desc->cpc_regs[reg_idx];
- return 0;
+ if (!CPC_SUPPORTED(reg)) {
+ pr_debug("CPC register (reg_idx=%d) is not supported\n", reg_idx);
+ return -EOPNOTSUPP;
+ }
Similarly to cppc_get_reg_val(), if a field is:
- mandatory + integer: currently doesn't exist. Not sure we should
try to detect that, but might be safer.
- mandatory + buffer: should not return -EOPNOTSUPP I think
- optional + integer: e.g.: 'Autonomous Selection Enable Register',
we should return -EOPNOTSUPP. It seems that currently, if the integer
value is 1, I get a 'write error: Bad address'
- optional + buffer:
should effectively return -EOPNOTSUPP if the buffer is NULL.
+
+ if (CPC_IN_PCC(reg))
+ return cppc_set_reg_val_in_pcc(cpu, reg, val);
+
+ return cpc_write(cpu, reg, val);
}
/**
@@ -1223,11 +1280,11 @@ static int cppc_get_perf(int cpunum, enum cppc_regs reg_idx, u64 *perf)
* @cpunum: CPU from which to get desired performance.
* @desired_perf: Return address.
*
- * Return: 0 for success, -EIO otherwise.
+ * Return: 0 for success, -ERRNO otherwise.
*/
int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
{
- return cppc_get_perf(cpunum, DESIRED_PERF, desired_perf);
+ return cppc_get_reg_val(cpunum, DESIRED_PERF, desired_perf);
}
EXPORT_SYMBOL_GPL(cppc_get_desired_perf);
@@ -1236,11 +1293,11 @@ EXPORT_SYMBOL_GPL(cppc_get_desired_perf);
* @cpunum: CPU from which to get nominal performance.
* @nominal_perf: Return address.
*
- * Return: 0 for success, -EIO otherwise.
+ * Return: 0 for success, -ERRNO otherwise.
*/
int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf)
{
- return cppc_get_perf(cpunum, NOMINAL_PERF, nominal_perf);
+ return cppc_get_reg_val(cpunum, NOMINAL_PERF, nominal_perf);
}
/**
@@ -1248,11 +1305,11 @@ int cppc_get_nominal_perf(int cpunum, u64 *nominal_perf)
* @cpunum: CPU from which to get highest performance.
* @highest_perf: Return address.
*
- * Return: 0 for success, -EIO otherwise.
+ * Return: 0 for success, -ERRNO otherwise.
*/
int cppc_get_highest_perf(int cpunum, u64 *highest_perf)
{
- return cppc_get_perf(cpunum, HIGHEST_PERF, highest_perf);
+ return cppc_get_reg_val(cpunum, HIGHEST_PERF, highest_perf);
}
EXPORT_SYMBOL_GPL(cppc_get_highest_perf);
@@ -1261,11 +1318,11 @@ EXPORT_SYMBOL_GPL(cppc_get_highest_perf);
* @cpunum: CPU from which to get epp preference value.
* @epp_perf: Return address.
*
- * Return: 0 for success, -EIO otherwise.
+ * Return: 0 for success, -ERRNO otherwise.
*/
int cppc_get_epp_perf(int cpunum, u64 *epp_perf)
{
- return cppc_get_perf(cpunum, ENERGY_PERF, epp_perf);
+ return cppc_get_reg_val(cpunum, ENERGY_PERF, epp_perf);
}
EXPORT_SYMBOL_GPL(cppc_get_epp_perf);