Read _SUB from ACPI to be able to identify firmware

PATCH Superseded Stefan Binding 5 participants 8 messages Jun 30, 2022 – Jul 5, 2022

Subsystems (4)

Sound ACPI ASoC Cirrus Logic audio codecs

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Stefan Binding

author

2022-06-30 15:01 UTC #0 lore raw

v5 cover Read _SUB from ACPI to be able to identify firmware

CS35L41 has a DSP which is able to run firmware, as well as a tuning file. Different systems may want to use different firmwares and tuning files, and some firmwares/tunings may not be compatible with other systems. To allow a system to select the correct fimware/tuning, we can read an _SUB from the ACPI. This _SUB can then be used to uniquely identify the system in the firmware/tuning file name.

Add a helper function which reads the _SUB, so this can be used by other parts in the future.
Add support inside the CS35L41 ASoC driver to read this _SUB, and save it appropriately.

Changes since v4:
- Rename function

Changes since v3:
- Fix 32 bit format string warning

Changes since v2:
- Fix error in function prototype

Changes since v1:
- Add length validation for SSID String
- Rename API
- Allocate memory inside API
- Use ACPI_HANDLE macro instead of ACPI_COMPANION
- Improve error handling

Stefan Binding (2):
ACPI: utils: Add api to read _SUB from ACPI
ASoC: cs35l41: Read System Name from ACPI _SUB to identify firmware

 drivers/acpi/utils.c       | 38 ++++++++++++++++++++++++++++++++++++++
 include/linux/acpi.h       |  6 ++++++
 sound/soc/codecs/cs35l41.c | 24 ++++++++++++++++++++++++
 3 files changed, 68 insertions(+)

Signature · 1 line

2.25.1

Stefan Binding

author

2022-06-30 15:01 UTC #1 lore raw

PATCH v5 1/2 ACPI: utils: Add api to read _SUB from ACPI

Add a wrapper function to read the _SUB string from ACPI.

Signed-off-by Stefan Binding <[email protected]>

---
 drivers/acpi/utils.c | 38 ++++++++++++++++++++++++++++++++++++++
 include/linux/acpi.h |  6 ++++++
 2 files changed, 44 insertions(+)

drivers/acpi/utils.c +38 -0

index 3a9773a09e19..394954f4b6ef 100644
@@ -291,6 +291,44 @@ int acpi_get_local_address(acpi_handle handle, u32 *addr)
 }
 EXPORT_SYMBOL(acpi_get_local_address);
 
+#define ACPI_MAX_SUB_BUF_SIZE	9
+
+const char *acpi_get_subsystem_id(acpi_handle handle)
+{
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *obj;
+	acpi_status status;
+	const char *sub;
+
+	status = acpi_evaluate_object(handle, METHOD_NAME__SUB, NULL, &buffer);
+	if (ACPI_FAILURE(status)) {
+		acpi_handle_debug(handle, "Reading ACPI _SUB failed: %#x\n", status);
+		return ERR_PTR(-ENODATA);
+	}
+
+	obj = buffer.pointer;
+	if (obj->type == ACPI_TYPE_STRING) {
+		if (strlen(obj->string.pointer) < ACPI_MAX_SUB_BUF_SIZE &&
+		    strlen(obj->string.pointer) > 0) {
+			sub = kstrdup(obj->string.pointer, GFP_KERNEL);
+			if (!sub)
+				sub = ERR_PTR(-ENOMEM);
+		} else {
+			acpi_handle_err(handle, "ACPI _SUB Length %zu is Invalid\n",
+					strlen(obj->string.pointer));
+			sub = ERR_PTR(-EINVAL);
+		}
+	} else {
+		acpi_handle_warn(handle, "Warning ACPI _SUB did not return a string\n");
+		sub = ERR_PTR(-EINVAL);
+	}
+
+	acpi_os_free(buffer.pointer);
+
+	return sub;
+}
+EXPORT_SYMBOL_GPL(acpi_get_subsystem_id);
+
 acpi_status
 acpi_evaluate_reference(acpi_handle handle,
 			acpi_string pathname,

include/linux/acpi.h +6 -0

index 7b96a8bff6d2..7651198ad6f5 100644
@@ -762,6 +762,7 @@ static inline u64 acpi_arch_get_root_pointer(void)
 #endif
 
 int acpi_get_local_address(acpi_handle handle, u32 *addr);
+const char *acpi_get_subsystem_id(acpi_handle handle);
 
 #else	/* !CONFIG_ACPI */

@@ -1023,6 +1024,11 @@ static inline int acpi_get_local_address(acpi_handle handle, u32 *addr)
 	return -ENODEV;
 }
 
+static inline const char *acpi_get_subsystem_id(acpi_handle handle)
+{
+	return ERR_PTR(-ENODEV);
+}
+
 static inline int acpi_register_wakeup_handler(int wake_irq,
 	bool (*wakeup)(void *context), void *context)
 {

Signature · 1 line

2.25.1

Rafael J. Wysocki

maintainer

2022-07-05 16:00 UTC #2 lore raw

Re: [PATCH v5 1/2] ACPI: utils: Add api to read _SUB from ACPI

Quoted 29 lines · Stefan Binding

Add a wrapper function to read the _SUB string from ACPI.

Signed-off-by Stefan Binding <[email protected]>

---
 drivers/acpi/utils.c | 38 ++++++++++++++++++++++++++++++++++++++
 include/linux/acpi.h |  6 ++++++
 2 files changed, 44 insertions(+)

drivers/acpi/utils.c +12 -0

index 3a9773a09e19..394954f4b6ef 100644
@@ -291,6 +291,44 @@ int acpi_get_local_address(acpi_handle handle, u32 *addr)
 }
 EXPORT_SYMBOL(acpi_get_local_address);
 
+#define ACPI_MAX_SUB_BUF_SIZE  9
+
+const char *acpi_get_subsystem_id(acpi_handle handle)
+{
+       struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+       union acpi_object *obj;
+       acpi_status status;
+       const char *sub;
+
+       status = acpi_evaluate_object(handle, METHOD_NAME__SUB, NULL, &buffer);
+       if (ACPI_FAILURE(status)) {
+               acpi_handle_debug(handle, "Reading ACPI _SUB failed: %#x\n", status);

drivers/acpi/utils.c int acpi_get_local_address(acpi_handle handle, u32 *addr) · line 315

Quoted 10 lines

drivers/acpi/utils.c +10 -0

+               return ERR_PTR(-ENODATA);
+       }
+
+       obj = buffer.pointer;
+       if (obj->type == ACPI_TYPE_STRING) {
+               if (strlen(obj->string.pointer) < ACPI_MAX_SUB_BUF_SIZE &&
+                   strlen(obj->string.pointer) > 0) {
+                       sub = kstrdup(obj->string.pointer, GFP_KERNEL);
+                       if (!sub)
+                               sub = ERR_PTR(-ENOMEM);

The error codes below are somewhat questionable.

drivers/acpi/utils.c int acpi_get_local_address(acpi_handle handle, u32 *addr) · line 319

Quoted 4 lines

drivers/acpi/utils.c +4 -0

+               } else {
+                       acpi_handle_err(handle, "ACPI _SUB Length %zu is Invalid\n",
+                                       strlen(obj->string.pointer));
+                       sub = ERR_PTR(-EINVAL);

This is as good as failure, so why not use -ENODATA here?

drivers/acpi/utils.c int acpi_get_local_address(acpi_handle handle, u32 *addr) · line 323

Quoted 4 lines

drivers/acpi/utils.c +4 -0

+               }
+       } else {
+               acpi_handle_warn(handle, "Warning ACPI _SUB did not return a string\n");
+               sub = ERR_PTR(-EINVAL);

Likewise.

Quoted 38 lines

drivers/acpi/utils.c +8 -0

+       }
+
+       acpi_os_free(buffer.pointer);
+
+       return sub;
+}
+EXPORT_SYMBOL_GPL(acpi_get_subsystem_id);
+
 acpi_status
 acpi_evaluate_reference(acpi_handle handle,
                        acpi_string pathname,

include/linux/acpi.h +6 -1

index 7b96a8bff6d2..7651198ad6f5 100644
@@ -762,6 +762,7 @@ static inline u64 acpi_arch_get_root_pointer(void)
 #endif
 
 int acpi_get_local_address(acpi_handle handle, u32 *addr);
+const char *acpi_get_subsystem_id(acpi_handle handle);
 
 #else  /* !CONFIG_ACPI */

@@ -1023,6 +1024,11 @@ static inline int acpi_get_local_address(acpi_handle handle, u32 *addr)
        return -ENODEV;
 }
 
+static inline const char *acpi_get_subsystem_id(acpi_handle handle)
+{
+       return ERR_PTR(-ENODEV);
+}
+
 static inline int acpi_register_wakeup_handler(int wake_irq,
        bool (*wakeup)(void *context), void *context)
 {
--

2.25.1

Andy Shevchenko

2022-07-05 19:06 UTC #3 lore raw

Re: [PATCH v5 1/2] ACPI: utils: Add api to read _SUB from ACPI

In reply to Stefan Binding

Quoted 2 lines · Stefan Binding

Add a wrapper function to read the _SUB string from ACPI.

...

drivers/acpi/utils.c int acpi_get_local_address(acpi_handle handle, u32 *addr) · line 318

Quoted 9 lines

drivers/acpi/utils.c +9 -0

+       if (obj->type == ACPI_TYPE_STRING) {
+               if (strlen(obj->string.pointer) < ACPI_MAX_SUB_BUF_SIZE &&
+                   strlen(obj->string.pointer) > 0) {
+                       sub = kstrdup(obj->string.pointer, GFP_KERNEL);
+                       if (!sub)
+                               sub = ERR_PTR(-ENOMEM);
+               } else {
+                       acpi_handle_err(handle, "ACPI _SUB Length %zu is Invalid\n",
+                                       strlen(obj->string.pointer));

Three times to evaluate strlen()... Can we do better, please?

Quoted 6 lines

drivers/acpi/utils.c +6 -0

+                       sub = ERR_PTR(-EINVAL);
+               }
+       } else {
+               acpi_handle_warn(handle, "Warning ACPI _SUB did not return a string\n");
+               sub = ERR_PTR(-EINVAL);
+       }

Signature · 2 lines

With Best Regards,
Andy Shevchenko

Stefan Binding

author

2022-06-30 15:02 UTC #4 lore raw

PATCH v5 2/2 ASoC: cs35l41: Read System Name from ACPI _SUB to identify firmware

In reply to Stefan Binding

When loading firmware, wm_adsp uses a number of parameters to determine the path of the firmware and tuning files to load. One of these parameters is system_name.
Add support in cs35l41 to read this system name from the ACPI _SUB ID in order to uniquely identify the firmware and tuning mapped to a particular system.

Signed-off-by Stefan Binding <[email protected]>

---
 sound/soc/codecs/cs35l41.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

sound/soc/codecs/cs35l41.c +24 -0

index 8766e19d85f1..d70469686699 100644
@@ -6,6 +6,7 @@
 //
 // Author: David Rhodes <[email protected]>
 
+#include <linux/acpi.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/init.h>

@@ -1142,6 +1143,24 @@ static int cs35l41_dsp_init(struct cs35l41_private *cs35l41)
 	return ret;
 }
 
+static int cs35l41_acpi_get_name(struct cs35l41_private *cs35l41)
+{
+	acpi_handle handle = ACPI_HANDLE(cs35l41->dev);
+	const char *sub;
+
+	/* If there is no ACPI_HANDLE, there is no ACPI for this system, return 0 */
+	if (!handle)
+		return 0;
+
+	sub = acpi_get_subsystem_id(handle);
+	if (IS_ERR(sub))
+		return PTR_ERR(sub);
+
+	cs35l41->dsp.system_name = sub;
+	dev_dbg(cs35l41->dev, "Susystem ID: %s\n", cs35l41->dsp.system_name);
+	return 0;
+}
+
 int cs35l41_probe(struct cs35l41_private *cs35l41, const struct cs35l41_hw_cfg *hw_cfg)
 {
 	u32 regid, reg_revid, i, mtl_revid, int_status, chipid_match;

@@ -1270,6 +1289,10 @@ int cs35l41_probe(struct cs35l41_private *cs35l41, const struct cs35l41_hw_cfg *
 		goto err;
 	}
 
+	ret = cs35l41_acpi_get_name(cs35l41);
+	if (ret < 0)
+		goto err;
+
 	ret = cs35l41_dsp_init(cs35l41);
 	if (ret < 0)
 		goto err;

@@ -1316,6 +1339,7 @@ void cs35l41_remove(struct cs35l41_private *cs35l41)
 	pm_runtime_disable(cs35l41->dev);
 
 	regmap_write(cs35l41->regmap, CS35L41_IRQ1_MASK1, 0xFFFFFFFF);
+	kfree(cs35l41->dsp.system_name);
 	wm_adsp2_remove(&cs35l41->dsp);
 	cs35l41_safe_reset(cs35l41->regmap, cs35l41->hw_cfg.bst_type);

Signature · 1 line

2.25.1

Pierre-Louis Bossart

2022-06-30 18:35 UTC #5 lore raw

Re: [PATCH v5 2/2] ASoC: cs35l41: Read System Name from ACPI _SUB to identify firmware

Quoted 6 lines · Stefan Binding

When loading firmware, wm_adsp uses a number of parameters to determine the path of the firmware and tuning files to load. One of these parameters is system_name.
Add support in cs35l41 to read this system name from the ACPI _SUB ID in order to uniquely identify the firmware and tuning mapped to a particular system.

It's my understanding that the _SUB method is optional, not required. It may be wise to plan for a fallback, e.g to use DMI quirks or other identifiers, no?

If it's used quite widely, then it may be a good thing to add to 'alsa-info'.

Quoted 26 lines

Signed-off-by Stefan Binding <[email protected]>

---
 sound/soc/codecs/cs35l41.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

sound/soc/codecs/cs35l41.c +6 -0

index 8766e19d85f1..d70469686699 100644
@@ -6,6 +6,7 @@
 //
 // Author: David Rhodes <[email protected]>
 
+#include <linux/acpi.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/init.h>

@@ -1142,6 +1143,24 @@ static int cs35l41_dsp_init(struct cs35l41_private *cs35l41)
 	return ret;
 }
 
+static int cs35l41_acpi_get_name(struct cs35l41_private *cs35l41)
+{
+	acpi_handle handle = ACPI_HANDLE(cs35l41->dev);
+	const char *sub;
+

sound/soc/codecs/cs35l41.c static int cs35l41_dsp_init(struct cs35l41_private *cs35l41) · line 1160

Quoted 10 lines

sound/soc/codecs/cs35l41.c +10 -0

+	/* If there is no ACPI_HANDLE, there is no ACPI for this system, return 0 */
+	if (!handle)
+		return 0;
+
+	sub = acpi_get_subsystem_id(handle);
+	if (IS_ERR(sub))
+		return PTR_ERR(sub);
+
+	cs35l41->dsp.system_name = sub;
+	dev_dbg(cs35l41->dev, "Susystem ID: %s\n", cs35l41->dsp.system_name);

Typo: Subsystem

Quoted 25 lines

sound/soc/codecs/cs35l41.c +8 -0

+	return 0;
+}
+
 int cs35l41_probe(struct cs35l41_private *cs35l41, const struct cs35l41_hw_cfg *hw_cfg)
 {
 	u32 regid, reg_revid, i, mtl_revid, int_status, chipid_match;

@@ -1270,6 +1289,10 @@ int cs35l41_probe(struct cs35l41_private *cs35l41, const struct cs35l41_hw_cfg *
 		goto err;
 	}
 
+	ret = cs35l41_acpi_get_name(cs35l41);
+	if (ret < 0)
+		goto err;
+
 	ret = cs35l41_dsp_init(cs35l41);
 	if (ret < 0)
 		goto err;

@@ -1316,6 +1339,7 @@ void cs35l41_remove(struct cs35l41_private *cs35l41)
 	pm_runtime_disable(cs35l41->dev);
 
 	regmap_write(cs35l41->regmap, CS35L41_IRQ1_MASK1, 0xFFFFFFFF);
+	kfree(cs35l41->dsp.system_name);
 	wm_adsp2_remove(&cs35l41->dsp);
 	cs35l41_safe_reset(cs35l41->regmap, cs35l41->hw_cfg.bst_type);

Mark Brown

maintainer

2022-06-30 19:34 UTC #6 lore raw

Re: [PATCH v5 2/2] ASoC: cs35l41: Read System Name from ACPI _SUB to identify firmware

Quoted 3 lines · Pierre-Louis Bossart

It's my understanding that the _SUB method is optional, not required. It may be wise to plan for a fallback, e.g to use DMI quirks or other identifiers, no?

Presumably the fallback would go into cs35l41_acpi_get_name()?

Pierre-Louis Bossart

2022-06-30 19:50 UTC #7 lore raw

Re: [PATCH v5 2/2] ASoC: cs35l41: Read System Name from ACPI _SUB to identify firmware

Quoted 7 lines · Mark Brown

Quoted 3 lines · Pierre-Louis Bossart
It's my understanding that the _SUB method is optional, not required. It may be wise to plan for a fallback, e.g to use DMI quirks or other identifiers, no?
Presumably the fallback would go into cs35l41_acpi_get_name()?

That's what I had in mind, if this _SUB does not exist then you could use something else instead of returning -ENODATA;

+ sub = acpi_get_subsystem_id(handle);
+ if (IS_ERR(sub))
+ return PTR_ERR(sub);
+
+ cs35l41->dsp.system_name = sub;