ASoC: SOF: Intel: hda-mlink: introduce helpers for 'extended links' PM

Add helpers to program SPA/CPA bits, using a mutex to access the
shared LCTL register if required.

All links are managed with the same LCTLx.SPA bits. However there are
quite a few implementation details to be aware of:

Legacy HDaudio multi-links are powered-up when exiting reset, which
requires the ref_count to be manually set to one when initializing the
link.

Alternate links for SoundWire/DMIC/SSP need to be explicitly
powered-up before accessing the SHIM/IP/Vendor-Specific SHIM space for
each sublink. DMIC/SSP/SoundWire are all different cases with a
different device/dai/hlink relationship.

SoundWire will handle power management with the auxiliary device
resume/suspend routine. The ref_count is not necessary in this case.

The DMIC/SSP will by contrast handle the power management from DAI
.startup and .shutdown callbacks.

The SSP has a 1:1 mapping between sublink and DAI, but it's
bidirectional so the ref_count will help avoid turning off the sublink
when one of the two directions is still in use.

The DMIC has a single link but two DAIs for data generated at
different sampling frequencies, again the ref_count will make sure the
two DAIs can be used concurrently.

And last the SoundWire Intel require power-up/down and bank switch to
be handled with a lock already taken, so the 'eml_lock' is made
optional with the _unlocked versions of the helpers.

Note that the _check_power_active() implementation is similar to
previous helpers in sound/hda/ext, with sleep duration and timeout
aligned with hardware recommendations. If desired, this helper could
be modified in a second step with .e.g. readl_poll_timeout()
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20230404104127.5629-9-peter.ujfalusi@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

include/sound/hda-mlink.h

@@ -12,6 +12,13 @@ struct hdac_bus;
 
 int hda_bus_ml_init(struct hdac_bus *bus);
 void hda_bus_ml_free(struct hdac_bus *bus);
+
+int hdac_bus_eml_power_up(struct hdac_bus *bus, bool alt, int elid, int sublink);
+int hdac_bus_eml_power_up_unlocked(struct hdac_bus *bus, bool alt, int elid, int sublink);
+
+int hdac_bus_eml_power_down(struct hdac_bus *bus, bool alt, int elid, int sublink);
+int hdac_bus_eml_power_down_unlocked(struct hdac_bus *bus, bool alt, int elid, int sublink);
+
 void hda_bus_ml_put_all(struct hdac_bus *bus);
 void hda_bus_ml_reset_losidv(struct hdac_bus *bus);
 int hda_bus_ml_resume(struct hdac_bus *bus);
@@ -23,6 +30,31 @@ static inline int
 hda_bus_ml_init(struct hdac_bus *bus) { return 0; }
 
 static inline void hda_bus_ml_free(struct hdac_bus *bus) { }
+
+static inline int
+hdac_bus_eml_power_up(struct hdac_bus *bus, bool alt, int elid, int sublink)
+{
+	return 0;
+}
+
+static inline int
+hdac_bus_eml_power_up_unlocked(struct hdac_bus *bus, bool alt, int elid, int sublink)
+{
+	return 0;
+}
+
+static inline int
+hdac_bus_eml_power_down(struct hdac_bus *bus, bool alt, int elid, int sublink)
+{
+	return 0;
+}
+
+static inline int
+hdac_bus_eml_power_down_unlocked(struct hdac_bus *bus, bool alt, int elid, int sublink)
+{
+	return 0;
+}
+
 static inline void hda_bus_ml_put_all(struct hdac_bus *bus) { }
 static inline void hda_bus_ml_reset_losidv(struct hdac_bus *bus) { }
 static inline int hda_bus_ml_resume(struct hdac_bus *bus) { return 0; }

sound/soc/sof/intel/hda-mlink.c

@@ -170,6 +170,68 @@ static int hdaml_lnk_enum(struct device *dev, struct hdac_ext2_link *h2link,
 	return 0;
 }
 
+/*
+ * Hardware recommendations are to wait ~10us before checking any hardware transition
+ * reported by bits changing status.
+ * This value does not need to be super-precise, a slack of 5us is perfectly acceptable.
+ * The worst-case is about 1ms before reporting an issue
+ */
+#define HDAML_POLL_DELAY_MIN_US 10
+#define HDAML_POLL_DELAY_SLACK_US 5
+#define HDAML_POLL_DELAY_RETRY  100
+
+static int check_sublink_power(u32 __iomem *lctl, int sublink, bool enabled)
+{
+	int mask = BIT(sublink) << AZX_ML_LCTL_CPA_SHIFT;
+	int retry = HDAML_POLL_DELAY_RETRY;
+	u32 val;
+
+	usleep_range(HDAML_POLL_DELAY_MIN_US,
+		     HDAML_POLL_DELAY_MIN_US + HDAML_POLL_DELAY_SLACK_US);
+	do {
+		val = readl(lctl);
+		if (enabled) {
+			if (val & mask)
+				return 0;
+		} else {
+			if (!(val & mask))
+				return 0;
+		}
+		usleep_range(HDAML_POLL_DELAY_MIN_US,
+			     HDAML_POLL_DELAY_MIN_US + HDAML_POLL_DELAY_SLACK_US);
+
+	} while (--retry);
+
+	return -EIO;
+}
+
+static int hdaml_link_init(u32 __iomem *lctl, int sublink)
+{
+	u32 val;
+	u32 mask = BIT(sublink) << AZX_ML_LCTL_SPA_SHIFT;
+
+	val = readl(lctl);
+	val |= mask;
+
+	writel(val, lctl);
+
+	return check_sublink_power(lctl, sublink, true);
+}
+
+static int hdaml_link_shutdown(u32 __iomem *lctl, int sublink)
+{
+	u32 val;
+	u32 mask;
+
+	val = readl(lctl);
+	mask = BIT(sublink) << AZX_ML_LCTL_SPA_SHIFT;
+	val &= ~mask;
+
+	writel(val, lctl);
+
+	return check_sublink_power(lctl, sublink, false);
+}
+
 /* END HDAML section */
 
 static int hda_ml_alloc_h2link(struct hdac_bus *bus, int index)
@@ -251,6 +313,107 @@ void hda_bus_ml_free(struct hdac_bus *bus)
 }
 EXPORT_SYMBOL_NS(hda_bus_ml_free, SND_SOC_SOF_HDA_MLINK);
 
+static struct hdac_ext2_link *
+find_ext2_link(struct hdac_bus *bus, bool alt, int elid)
+{
+	struct hdac_ext_link *hlink;
+
+	list_for_each_entry(hlink, &bus->hlink_list, list) {
+		struct hdac_ext2_link *h2link = hdac_ext_link_to_ext2(hlink);
+
+		if (h2link->alt == alt && h2link->elid == elid)
+			return h2link;
+	}
+
+	return NULL;
+}
+
+static int hdac_bus_eml_power_up_base(struct hdac_bus *bus, bool alt, int elid, int sublink,
+				      bool eml_lock)
+{
+	struct hdac_ext2_link *h2link;
+	struct hdac_ext_link *hlink;
+	int ret = 0;
+
+	h2link = find_ext2_link(bus, alt, elid);
+	if (!h2link)
+		return -ENODEV;
+
+	if (sublink >= h2link->slcount)
+		return -EINVAL;
+
+	hlink = &h2link->hext_link;
+
+	if (eml_lock)
+		mutex_lock(&h2link->eml_lock);
+
+	if (++hlink->ref_count > 1)
+		goto skip_init;
+
+	ret = hdaml_link_init(hlink->ml_addr + AZX_REG_ML_LCTL, sublink);
+
+skip_init:
+	if (eml_lock)
+		mutex_unlock(&h2link->eml_lock);
+
+	return ret;
+}
+
+int hdac_bus_eml_power_up(struct hdac_bus *bus, bool alt, int elid, int sublink)
+{
+	return hdac_bus_eml_power_up_base(bus, alt, elid, sublink, true);
+}
+EXPORT_SYMBOL_NS(hdac_bus_eml_power_up, SND_SOC_SOF_HDA_MLINK);
+
+int hdac_bus_eml_power_up_unlocked(struct hdac_bus *bus, bool alt, int elid, int sublink)
+{
+	return hdac_bus_eml_power_up_base(bus, alt, elid, sublink, false);
+}
+EXPORT_SYMBOL_NS(hdac_bus_eml_power_up_unlocked, SND_SOC_SOF_HDA_MLINK);
+
+static int hdac_bus_eml_power_down_base(struct hdac_bus *bus, bool alt, int elid, int sublink,
+					bool eml_lock)
+{
+	struct hdac_ext2_link *h2link;
+	struct hdac_ext_link *hlink;
+	int ret = 0;
+
+	h2link = find_ext2_link(bus, alt, elid);
+	if (!h2link)
+		return -ENODEV;
+
+	if (sublink >= h2link->slcount)
+		return -EINVAL;
+
+	hlink = &h2link->hext_link;
+
+	if (eml_lock)
+		mutex_lock(&h2link->eml_lock);
+
+	if (--hlink->ref_count > 0)
+		goto skip_shutdown;
+
+	ret = hdaml_link_shutdown(hlink->ml_addr + AZX_REG_ML_LCTL, sublink);
+
+skip_shutdown:
+	if (eml_lock)
+		mutex_unlock(&h2link->eml_lock);
+
+	return ret;
+}
+
+int hdac_bus_eml_power_down(struct hdac_bus *bus, bool alt, int elid, int sublink)
+{
+	return hdac_bus_eml_power_down_base(bus, alt, elid, sublink, true);
+}
+EXPORT_SYMBOL_NS(hdac_bus_eml_power_down, SND_SOC_SOF_HDA_MLINK);
+
+int hdac_bus_eml_power_down_unlocked(struct hdac_bus *bus, bool alt, int elid, int sublink)
+{
+	return hdac_bus_eml_power_down_base(bus, alt, elid, sublink, false);
+}
+EXPORT_SYMBOL_NS(hdac_bus_eml_power_down_unlocked, SND_SOC_SOF_HDA_MLINK);
+
 void hda_bus_ml_put_all(struct hdac_bus *bus)
 {
 	struct hdac_ext_link *hlink;