ASoC: cs-amp-lib: Add helpers for factory calibration data

Create a new library for code that is used by multiple Cirrus Logic
amps. This initially implements extracting amp calibration data
from EFI and writing it to firmware controls.

During factory calibration of built-in speakers the firmware
calibration constants are stored in an EFI file. The file contains
an array of calibration constants for each of the speakers.
cs_amp_get_calibration_data() searches for an entry matching the
requested UID stamp, otherwise by array index. If the data is found in
EFI the constants for that speaker are copied back to the caller.

If EFI is not enabled, the cs_amp_get_calibration_data() implementation
will compile to simply return -ENOENT and the linker can drop the code.

The code to write calibration controls uses cs_dsp. Building of cs_dsp
is not forced. Instead, the code will compile away the calls to
cs_dsp if cs_dsp is not reachable.

This strategy of conditional code allows cs-amp-lib to be shared by
multiple drivers without forcing inclusion of other modules that might
be unnecessary.

The calls to efi.get_variable() and cs_dsp are in small wrapper
functions. This is so that a KUNIT_STATIC_STUB_REDIRECT can be added in
a future patch to redirect these calls to replacement functions for
KUnit testing.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20240223153910.2063698-3-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

3 files changed, 268 insertions, 0 deletions

diff --git a/sound/soc/codecs/Kconfig b/sound/soc/codecs/Kconfig
index 59f9742e9ff49a..109848a7a413c3 100644
--- a/sound/soc/codecs/Kconfig
+++ b/sound/soc/codecs/Kconfig
@@ -727,6 +727,9 @@ config SND_SOC_CROS_EC_CODEC
 	  If you say yes here you will get support for the
 	  ChromeOS Embedded Controller's Audio Codec.
 
+config SND_SOC_CS_AMP_LIB
+	tristate
+
 config SND_SOC_CS35L32
 	tristate "Cirrus Logic CS35L32 CODEC"
 	depends on I2C
diff --git a/sound/soc/codecs/Makefile b/sound/soc/codecs/Makefile
index f53baa2b956519..0caa3209673b4b 100644
--- a/sound/soc/codecs/Makefile
+++ b/sound/soc/codecs/Makefile
@@ -59,6 +59,7 @@ snd-soc-chv3-codec-objs := chv3-codec.o
 snd-soc-cpcap-objs := cpcap.o
 snd-soc-cq93vc-objs := cq93vc.o
 snd-soc-cros-ec-codec-objs := cros_ec_codec.o
+snd-soc-cs-amp-lib-objs := cs-amp-lib.o
 snd-soc-cs35l32-objs := cs35l32.o
 snd-soc-cs35l33-objs := cs35l33.o
 snd-soc-cs35l34-objs := cs35l34.o
@@ -449,6 +450,7 @@ obj-$(CONFIG_SND_SOC_CHV3_CODEC) += snd-soc-chv3-codec.o
 obj-$(CONFIG_SND_SOC_CQ0093VC) += snd-soc-cq93vc.o
 obj-$(CONFIG_SND_SOC_CPCAP)	+= snd-soc-cpcap.o
 obj-$(CONFIG_SND_SOC_CROS_EC_CODEC)	+= snd-soc-cros-ec-codec.o
+obj-$(CONFIG_SND_SOC_CS_AMP_LIB)	+= snd-soc-cs-amp-lib.o
 obj-$(CONFIG_SND_SOC_CS35L32)	+= snd-soc-cs35l32.o
 obj-$(CONFIG_SND_SOC_CS35L33)	+= snd-soc-cs35l33.o
 obj-$(CONFIG_SND_SOC_CS35L34)	+= snd-soc-cs35l34.o
diff --git a/sound/soc/codecs/cs-amp-lib.c b/sound/soc/codecs/cs-amp-lib.c
new file mode 100644
index 00000000000000..4e2e5157a73f87
--- /dev/null
+++ b/sound/soc/codecs/cs-amp-lib.c
@@ -0,0 +1,263 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Common code for Cirrus Logic Smart Amplifiers
+//
+// Copyright (C) 2024 Cirrus Logic, Inc. and
+//               Cirrus Logic International Semiconductor Ltd.
+
+#include <asm/byteorder.h>
+#include <linux/dev_printk.h>
+#include <linux/efi.h>
+#include <linux/firmware/cirrus/cs_dsp.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <sound/cs-amp-lib.h>
+
+#define CS_AMP_CAL_GUID \
+	EFI_GUID(0x02f9af02, 0x7734, 0x4233, 0xb4, 0x3d, 0x93, 0xfe, 0x5a, 0xa3, 0x5d, 0xb3)
+
+#define CS_AMP_CAL_NAME	L"CirrusSmartAmpCalibrationData"
+
+static int cs_amp_write_cal_coeff(struct cs_dsp *dsp,
+				  const struct cirrus_amp_cal_controls *controls,
+				  const char *ctl_name, u32 val)
+{
+	struct cs_dsp_coeff_ctl *cs_ctl;
+	__be32 beval = cpu_to_be32(val);
+	int ret;
+
+	if (IS_REACHABLE(CONFIG_FW_CS_DSP)) {
+		mutex_lock(&dsp->pwr_lock);
+		cs_ctl = cs_dsp_get_ctl(dsp, ctl_name, controls->mem_region, controls->alg_id);
+		ret = cs_dsp_coeff_write_ctrl(cs_ctl, 0, &beval, sizeof(beval));
+		mutex_unlock(&dsp->pwr_lock);
+
+		if (ret < 0) {
+			dev_err(dsp->dev, "Failed to write to '%s': %d\n", ctl_name, ret);
+			return ret;
+		}
+
+		return 0;
+	}
+
+	return -ENODEV;
+}
+
+static int _cs_amp_write_cal_coeffs(struct cs_dsp *dsp,
+				    const struct cirrus_amp_cal_controls *controls,
+				    const struct cirrus_amp_cal_data *data)
+{
+	int ret;
+
+	dev_dbg(dsp->dev, "Calibration: Ambient=%#x, Status=%#x, CalR=%d\n",
+		data->calAmbient, data->calStatus, data->calR);
+
+	ret = cs_amp_write_cal_coeff(dsp, controls, controls->ambient, data->calAmbient);
+	if (ret)
+		return ret;
+
+	ret = cs_amp_write_cal_coeff(dsp, controls, controls->calr, data->calR);
+	if (ret)
+		return ret;
+
+	ret = cs_amp_write_cal_coeff(dsp, controls, controls->status, data->calStatus);
+	if (ret)
+		return ret;
+
+	ret = cs_amp_write_cal_coeff(dsp, controls, controls->checksum, data->calR + 1);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+/**
+ * cs_amp_write_cal_coeffs - Write calibration data to firmware controls.
+ * @dsp:	Pointer to struct cs_dsp.
+ * @controls:	Pointer to definition of firmware controls to be written.
+ * @data:	Pointer to calibration data.
+ *
+ * Returns: 0 on success, else negative error value.
+ */
+int cs_amp_write_cal_coeffs(struct cs_dsp *dsp,
+			    const struct cirrus_amp_cal_controls *controls,
+			    const struct cirrus_amp_cal_data *data)
+{
+	if (IS_REACHABLE(CONFIG_FW_CS_DSP))
+		return _cs_amp_write_cal_coeffs(dsp, controls, data);
+	else
+		return -ENODEV;
+}
+EXPORT_SYMBOL_NS_GPL(cs_amp_write_cal_coeffs, SND_SOC_CS_AMP_LIB);
+
+static efi_status_t cs_amp_get_efi_variable(efi_char16_t *name,
+					    efi_guid_t *guid,
+					    unsigned long *size,
+					    void *buf)
+{
+	u32 attr;
+
+	if (IS_ENABLED(CONFIG_EFI))
+		return efi.get_variable(name, guid, &attr, size, buf);
+
+	return EFI_NOT_FOUND;
+}
+
+static struct cirrus_amp_efi_data *cs_amp_get_cal_efi_buffer(struct device *dev)
+{
+	struct cirrus_amp_efi_data *efi_data;
+	unsigned long data_size = 0;
+	u8 *data;
+	efi_status_t status;
+	int ret;
+
+	/* Get real size of UEFI variable */
+	status = cs_amp_get_efi_variable(CS_AMP_CAL_NAME, &CS_AMP_CAL_GUID, &data_size, NULL);
+	if (status != EFI_BUFFER_TOO_SMALL)
+		return ERR_PTR(-ENOENT);
+
+	if (data_size < sizeof(*efi_data)) {
+		dev_err(dev, "EFI cal variable truncated\n");
+		return ERR_PTR(-EOVERFLOW);
+	}
+
+	/* Get variable contents into buffer */
+	data = kmalloc(data_size, GFP_KERNEL);
+	if (!data)
+		return ERR_PTR(-ENOMEM);
+
+	status = cs_amp_get_efi_variable(CS_AMP_CAL_NAME, &CS_AMP_CAL_GUID, &data_size, data);
+	if (status != EFI_SUCCESS) {
+		ret = -EINVAL;
+		goto err;
+	}
+
+	efi_data = (struct cirrus_amp_efi_data *)data;
+	dev_dbg(dev, "Calibration: Size=%d, Amp Count=%d\n", efi_data->size, efi_data->count);
+
+	if ((efi_data->count > 128) ||
+	    offsetof(struct cirrus_amp_efi_data, data[efi_data->count]) > data_size) {
+		dev_err(dev, "EFI cal variable truncated\n");
+		ret = -EOVERFLOW;
+		goto err;
+	}
+
+	return efi_data;
+
+err:
+	kfree(data);
+	dev_err(dev, "Failed to read calibration data from EFI: %d\n", ret);
+
+	return ERR_PTR(ret);
+}
+
+static u64 cs_amp_cal_target_u64(const struct cirrus_amp_cal_data *data)
+{
+	return ((u64)data->calTarget[1] << 32) | data->calTarget[0];
+}
+
+static int _cs_amp_get_efi_calibration_data(struct device *dev, u64 target_uid, int amp_index,
+					    struct cirrus_amp_cal_data *out_data)
+{
+	struct cirrus_amp_efi_data *efi_data;
+	struct cirrus_amp_cal_data *cal = NULL;
+	int i, ret;
+
+	efi_data = cs_amp_get_cal_efi_buffer(dev);
+	if (IS_ERR(efi_data))
+		return PTR_ERR(efi_data);
+
+	if (target_uid) {
+		for (i = 0; i < efi_data->count; ++i) {
+			u64 cal_target = cs_amp_cal_target_u64(&efi_data->data[i]);
+
+			/* Skip entries with unpopulated silicon ID */
+			if (cal_target == 0)
+				continue;
+
+			if (cal_target == target_uid) {
+				cal = &efi_data->data[i];
+				break;
+			}
+		}
+	}
+
+	if (!cal && (amp_index >= 0) && (amp_index < efi_data->count)) {
+		u64 cal_target = cs_amp_cal_target_u64(&efi_data->data[amp_index]);
+
+		/*
+		 * Treat unpopulated cal_target as a wildcard.
+		 * If target_uid != 0 we can only get here if cal_target == 0
+		 * or it didn't match any cal_target value.
+		 * If target_uid == 0 it is a wildcard.
+		 */
+		if ((cal_target == 0) || (target_uid == 0))
+			cal = &efi_data->data[amp_index];
+		else
+			dev_warn(dev, "Calibration entry %d does not match silicon ID", amp_index);
+	}
+
+	if (cal) {
+		memcpy(out_data, cal, sizeof(*out_data));
+		ret = 0;
+	} else {
+		dev_warn(dev, "No calibration for silicon ID %#llx\n", target_uid);
+		ret = -ENOENT;
+	}
+
+	kfree(efi_data);
+
+	return ret;
+}
+
+/**
+ * cs_amp_get_efi_calibration_data - get an entry from calibration data in EFI.
+ * @dev:	struct device of the caller.
+ * @target_uid:	UID to match, or zero to ignore UID matching.
+ * @amp_index:	Entry index to use, or -1 to prevent lookup by index.
+ * @out_data:	struct cirrus_amp_cal_data where the entry will be copied.
+ *
+ * This function can perform 3 types of lookup:
+ *
+ * (target_uid > 0, amp_index >= 0)
+ *	UID search with fallback to using the array index.
+ *	Search the calibration data for a non-zero calTarget that matches
+ *	target_uid, and if found return that entry. Else, if the entry at
+ *	[amp_index] has calTarget == 0, return that entry. Else fail.
+ *
+ * (target_uid > 0, amp_index < 0)
+ *	UID search only.
+ *	Search the calibration data for a non-zero calTarget that matches
+ *	target_uid, and if found return that entry. Else fail.
+ *
+ * (target_uid == 0, amp_index >= 0)
+ *	Array index fetch only.
+ *	Return the entry at [amp_index].
+ *
+ * An array lookup will be skipped if amp_index exceeds the number of
+ * entries in the calibration array, and in this case the return will
+ * be -ENOENT. An out-of-range amp_index does not prevent matching by
+ * target_uid - it has the same effect as passing amp_index < 0.
+ *
+ * If the EFI data is too short to be a valid entry, or the entry count
+ * in the EFI data overflows the actual length of the data, this function
+ * returns -EOVERFLOW.
+ *
+ * Return: 0 if the entry was found, -ENOENT if no entry was found,
+ *	   -EOVERFLOW if the EFI file is corrupt, else other error value.
+ */
+int cs_amp_get_efi_calibration_data(struct device *dev, u64 target_uid, int amp_index,
+				    struct cirrus_amp_cal_data *out_data)
+{
+	if (IS_ENABLED(CONFIG_EFI))
+		return _cs_amp_get_efi_calibration_data(dev, target_uid, amp_index, out_data);
+	else
+		return -ENOENT;
+}
+EXPORT_SYMBOL_NS_GPL(cs_amp_get_efi_calibration_data, SND_SOC_CS_AMP_LIB);
+
+MODULE_DESCRIPTION("Cirrus Logic amplifier library");
+MODULE_AUTHOR("Richard Fitzgerald <rf@opensource.cirrus.com>");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(FW_CS_DSP);