[PATCH 08/11] ASoC: cs-amp-lib: Add function to write calibration to EFI

Richard Fitzgerald
2025-10-16T10:42:58Z

Add cs_amp_set_efi_calibration_data() to write an amp calibration
blob to EFI calibration variable.

The EFI variable will be updated or created as necessary.

- If a Vendor-specific variable exists it will be updated,
else if the Cirrus variable exists it will be update
else the Cirrus variable will be created.

Some collateral changes are required:

- cs_amp_convert_efi_status() now specifically handles
EFI_WRITE_PROTECTED error.

- cs_amp_get_cal_efi_buffer() can optionally return the name,
guid and attr of the variable it found.

- cs_amp_get_cal_efi_buffer() will update the 'size' field of
the returned data blob if it is zero. The BIOS could have
pre-allocated the EFI variable as zero-filled

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
---
include/sound/cs-amp-lib.h | 2 +
sound/soc/codecs/cs-amp-lib.c | 190 +++++++++++++++++++++++++++++++++-
2 files changed, 188 insertions(+), 4 deletions(-)

diff --git a/include/sound/cs-amp-lib.h b/include/sound/cs-amp-lib.h
index 09c54b1bbe6c..4c8b84ee087e 100644
--- a/include/sound/cs-amp-lib.h
+++ b/include/sound/cs-amp-lib.h
@@ -55,6 +55,8 @@ int cs_amp_write_ambient_temp(struct cs_dsp *dsp,
u32 temp);
int cs_amp_get_efi_calibration_data(struct device *dev, u64 target_uid, int amp_index,
struct cirrus_amp_cal_data *out_data);
+int cs_amp_set_efi_calibration_data(struct device *dev, int amp_index, int num_amps,
+ const struct cirrus_amp_cal_data *in_data);
int cs_amp_get_vendor_spkid(struct device *dev);

static inline u64 cs_amp_cal_target_u64(const struct cirrus_amp_cal_data *data)
diff --git a/sound/soc/codecs/cs-amp-lib.c b/sound/soc/codecs/cs-amp-lib.c
index 2630ea6a8f3a..3f352ecad3e0 100644
--- a/sound/soc/codecs/cs-amp-lib.c
+++ b/sound/soc/codecs/cs-amp-lib.c
@@ -12,6 +12,7 @@
#include <linux/firmware/cirrus/cs_dsp.h>
#include <linux/math64.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include <linux/overflow.h>
#include <linux/slab.h>
#include <linux/timekeeping.h>
@@ -48,9 +49,16 @@ static const struct cs_amp_lib_cal_efivar {
},
};

+#define CS_AMP_CAL_DEFAULT_EFI_ATTR \
+ (EFI_VARIABLE_NON_VOLATILE | \
+ EFI_VARIABLE_BOOTSERVICE_ACCESS | \
+ EFI_VARIABLE_RUNTIME_ACCESS)
+
/* Offset from Unix time to Windows time (100ns since 1 Jan 1601) */
#define UNIX_TIME_TO_WINDOWS_TIME_OFFSET 116444736000000000ULL

+static DEFINE_MUTEX(cs_amp_efi_cal_write_lock);
+
static u64 cs_amp_time_now_in_windows_time(void)
{
u64 time_in_100ns = div_u64(ktime_get_real_ns(), 100);
@@ -262,6 +270,20 @@ static efi_status_t cs_amp_get_efi_variable(efi_char16_t *name,
return EFI_NOT_FOUND;
}

+static efi_status_t cs_amp_set_efi_variable(efi_char16_t *name,
+ efi_guid_t *guid,
+ u32 attr,
+ unsigned long size,
+ void *buf)
+{
+ KUNIT_STATIC_STUB_REDIRECT(cs_amp_set_efi_variable, name, guid, attr, size, buf);
+
+ if (!efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE))
+ return EFI_NOT_FOUND;
+
+ return efi.set_variable(name, guid, attr, size, buf);
+}
+
static int cs_amp_convert_efi_status(efi_status_t status)
{
switch (status) {
@@ -271,6 +293,7 @@ static int cs_amp_convert_efi_status(efi_status_t status)
return -ENOENT;
case EFI_BUFFER_TOO_SMALL:
return -EFBIG;
+ case EFI_WRITE_PROTECTED:
case EFI_UNSUPPORTED:
case EFI_ACCESS_DENIED:
case EFI_SECURITY_VIOLATION:
@@ -280,7 +303,10 @@ static int cs_amp_convert_efi_status(efi_status_t status)
}
}

-static struct cirrus_amp_efi_data *cs_amp_get_cal_efi_buffer(struct device *dev)
+static struct cirrus_amp_efi_data *cs_amp_get_cal_efi_buffer(struct device *dev,
+ efi_char16_t **name,
+ efi_guid_t **guid,
+ u32 *attr)
{
struct cirrus_amp_efi_data *efi_data;
unsigned long data_size = 0;
@@ -292,7 +318,7 @@ static struct cirrus_amp_efi_data *cs_amp_get_cal_efi_buffer(struct device *dev)
for (i = 0; i < ARRAY_SIZE(cs_amp_lib_cal_efivars); i++) {
status = cs_amp_get_efi_variable(cs_amp_lib_cal_efivars[i].name,
cs_amp_lib_cal_efivars[i].guid,
- NULL, &data_size, NULL);
+ attr, &data_size, NULL);
if (status == EFI_BUFFER_TOO_SMALL)
break;
}
@@ -300,6 +326,12 @@ static struct cirrus_amp_efi_data *cs_amp_get_cal_efi_buffer(struct device *dev)
if (status != EFI_BUFFER_TOO_SMALL)
return ERR_PTR(-ENOENT);

+ if (name)
+ *name = cs_amp_lib_cal_efivars[i].name;
+
+ if (guid)
+ *guid = cs_amp_lib_cal_efivars[i].guid;
+
if (data_size < sizeof(*efi_data)) {
dev_err(dev, "EFI cal variable truncated\n");
return ERR_PTR(-EOVERFLOW);
@@ -312,7 +344,7 @@ static struct cirrus_amp_efi_data *cs_amp_get_cal_efi_buffer(struct device *dev)

status = cs_amp_get_efi_variable(cs_amp_lib_cal_efivars[i].name,
cs_amp_lib_cal_efivars[i].guid,
- NULL, &data_size, data);
+ attr, &data_size, data);
if (status != EFI_SUCCESS) {
ret = -EINVAL;
goto err;
@@ -328,6 +360,10 @@ static struct cirrus_amp_efi_data *cs_amp_get_cal_efi_buffer(struct device *dev)
goto err;
}

+ /* This could be zero-filled space pre-allocated by the BIOS */
+ if (efi_data->size == 0)
+ efi_data->size = data_size;
+
return efi_data;

err:
@@ -337,6 +373,20 @@ static struct cirrus_amp_efi_data *cs_amp_get_cal_efi_buffer(struct device *dev)
return ERR_PTR(ret);
}

+static int cs_amp_set_cal_efi_buffer(struct device *dev,
+ efi_char16_t *name,
+ efi_guid_t *guid,
+ u32 attr,
+ struct cirrus_amp_efi_data *data)
+{
+ efi_status_t status;
+
+ status = cs_amp_set_efi_variable(name, guid, attr,
+ struct_size(data, data, data->count), data);
+
+ return cs_amp_convert_efi_status(status);
+}
+
static int _cs_amp_get_efi_calibration_data(struct device *dev, u64 target_uid, int amp_index,
struct cirrus_amp_cal_data *out_data)
{
@@ -344,7 +394,7 @@ static int _cs_amp_get_efi_calibration_data(struct device *dev, u64 target_uid,
struct cirrus_amp_cal_data *cal = NULL;
int i, ret;

- efi_data = cs_amp_get_cal_efi_buffer(dev);
+ efi_data = cs_amp_get_cal_efi_buffer(dev, NULL, NULL, NULL);
if (IS_ERR(efi_data))
return PTR_ERR(efi_data);

@@ -396,6 +446,98 @@ static int _cs_amp_get_efi_calibration_data(struct device *dev, u64 target_uid,
return ret;
}

+static int _cs_amp_set_efi_calibration_data(struct device *dev, int amp_index, int num_amps,
+ const struct cirrus_amp_cal_data *in_data)
+{
+ u64 cal_target = cs_amp_cal_target_u64(in_data);
+ unsigned long num_entries;
+ struct cirrus_amp_efi_data *data __free(kfree) = NULL;
+ efi_char16_t *name = CIRRUS_LOGIC_CALIBRATION_EFI_NAME;
+ efi_guid_t *guid = &CIRRUS_LOGIC_CALIBRATION_EFI_GUID;
+ u32 attr = CS_AMP_CAL_DEFAULT_EFI_ATTR;
+ int i, ret;
+
+ if (cal_target == 0)
+ return -EINVAL;
+
+ data = cs_amp_get_cal_efi_buffer(dev, &name, &guid, &attr);
+ ret = PTR_ERR_OR_ZERO(data);
+ if (ret == -ENOENT) {
+ data = NULL;
+ goto alloc_new;
+ } else if (ret) {
+ return ret;
+ }
+
+ /*
+ * If the EFI variable is just zero-filled reserved space the count
+ * must be set.
+ */
+ if (data->count == 0)
+ data->count = (data->size - sizeof(data)) / sizeof(data->data[0]);
+
+ if (amp_index < 0) {
+ /* Is there already a slot for this target? */
+ for (amp_index = 0; amp_index < data->count; amp_index++) {
+ if (cs_amp_cal_target_u64(&data->data[amp_index]) == cal_target)
+ break;
+ }
+
+ /* Else find an empty slot */
+ if (amp_index >= data->count) {
+ for (amp_index = 0; amp_index < data->count; amp_index++) {
+ if ((data->data[amp_index].calTime[0] == 0) &&
+ (data->data[amp_index].calTime[1] == 0))
+ break;
+ }
+ }
+ } else {
+ /*
+ * If the index is forced there could be another active
+ * slot with the same calTarget. So deduplicate.
+ */
+ for (i = 0; i < data->count; i++) {
+ if (i == amp_index)
+ continue;
+
+ if ((data->data[i].calTime[0] == 0) && (data->data[i].calTime[1] == 0))
+ continue;
+
+ if (cs_amp_cal_target_u64(&data->data[i]) == cal_target)
+ memset(data->data[i].calTime, 0, sizeof(data->data[i].calTime));
+ }
+ }
+
+alloc_new:
+ if (amp_index < 0)
+ amp_index = 0;
+
+ num_entries = max(num_amps, amp_index + 1);
+ if (!data || (data->count < num_entries)) {
+ struct cirrus_amp_efi_data *old_data __free(kfree) = no_free_ptr(data);
+ unsigned int new_data_size = struct_size(data, data, num_entries);
+
+ data = kzalloc(new_data_size, GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ if (old_data)
+ memcpy(data, old_data, struct_size(old_data, data, old_data->count));
+
+ data->count = num_entries;
+ data->size = new_data_size;
+ }
+
+ data->data[amp_index] = *in_data;
+ ret = cs_amp_set_cal_efi_buffer(dev, name, guid, attr, data);
+ if (ret) {
+ dev_err(dev, "Failed writing calibration to EFI: %d\n", ret);
+ return ret;
+ }
+
+ return 0;
+}
+
/**
* cs_amp_get_efi_calibration_data - get an entry from calibration data in EFI.
* @dev: struct device of the caller.
@@ -442,6 +584,46 @@ int cs_amp_get_efi_calibration_data(struct device *dev, u64 target_uid, int amp_
}
EXPORT_SYMBOL_NS_GPL(cs_amp_get_efi_calibration_data, "SND_SOC_CS_AMP_LIB");

+/**
+ * cs_amp_set_efi_calibration_data - write a calibration data entry to EFI.
+ * @dev: struct device of the caller.
+ * @amp_index: Entry index to use, or -1 to use any available slot.
+ * @num_amps: Maximum number of amps to reserve slots for, or -1 to ignore.
+ * @in_data: struct cirrus_amp_cal_data entry to be written to EFI.
+ *
+ * If a Vendor-specific variable exists it will be updated,
+ * else if the Cirrus variable exists it will be updated
+ * else the Cirrus variable will be created.
+ *
+ * If amp_index >= 0 the data will be placed in this entry of the calibration
+ * data array, overwriting what was in that entry. Any other entries with the
+ * same calTarget will be marked empty.
+ *
+ * If amp_index < 0 and in_data->calTarget matches any existing entry, that
+ * entry will be overwritten. Else the first available free entry will be used,
+ * extending the size of the EFI variable if there are no free entries.
+ *
+ * If num_amps > 0 the EFI variable will be sized to contain at least this
+ * many calibration entries, with any new entries marked empty.
+ *
+ * Return: 0 if the write was successful, -EFBIG if space could not be made in
+ * the EFI file to add the entry, -EACCES if it was not possible to
+ * read or write the EFI variable.
+ */
+int cs_amp_set_efi_calibration_data(struct device *dev, int amp_index, int num_amps,
+ const struct cirrus_amp_cal_data *in_data)
+{
+ if (IS_ENABLED(CONFIG_EFI) || IS_ENABLED(CONFIG_SND_SOC_CS_AMP_LIB_TEST)) {
+ scoped_guard(mutex, &cs_amp_efi_cal_write_lock) {
+ return _cs_amp_set_efi_calibration_data(dev, amp_index,
+ num_amps, in_data);
+ }
+ }
+
+ return -ENOENT;
+}
+EXPORT_SYMBOL_NS_GPL(cs_amp_set_efi_calibration_data, "SND_SOC_CS_AMP_LIB");
+
struct cs_amp_spkid_efi {
efi_char16_t *name;
efi_guid_t *guid;
--
2.47.3