ALSA: hda: Direct MMIO accesses

HD-audio drivers access to the mmio registers indirectly via the
corresponding bus->io_ops callbacks.  This is because some platform
(notably Tegra SoC) requires the word-aligned access.  But it's rather
a rare case, and other platforms suffer from the penalties by indirect
calls unnecessarily.

This patch is an attempt to optimize and cleanup for this situation.
Now the special aligned access is used only when a new kconfig
CONFIG_SND_HDA_ALIGNED_MMIO is set.  And the HD-audio core itself
provides the aligned MMIO access helpers instead of the driver side.
If Kconfig isn't set (as default), the standard helpers like readl()
or writel() are used directly.

A couple of places in ASoC Intel drivers have the access via io_ops
reg_writel(), and they are replaced with the direct writel() calls.

And now with this patch, the whole bus->io_ops becomes empty, so it's
dropped completely.  The bus initialization functions are changed
accordingly as well to drop the whole bus->io_ops.

Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 31 insertions, 4 deletions

diff --git a/sound/hda/hdac_bus.c b/sound/hda/hdac_bus.c
index 00ea12e67dc8..dc2523ef7d98 100644
--- a/sound/hda/hdac_bus.c
+++ b/sound/hda/hdac_bus.c
@@ -19,13 +19,11 @@ static const struct hdac_bus_ops default_ops = {
  * snd_hdac_bus_init - initialize a HD-audio bas bus
  * @bus: the pointer to bus object
  * @ops: bus verb operators
- * @io_ops: lowlevel I/O operators
  *
  * Returns 0 if successful, or a negative error code.
  */
 int snd_hdac_bus_init(struct hdac_bus *bus, struct device *dev,
-		      const struct hdac_bus_ops *ops,
-		      const struct hdac_io_ops *io_ops)
+		      const struct hdac_bus_ops *ops)
 {
 	memset(bus, 0, sizeof(*bus));
 	bus->dev = dev;
@@ -33,7 +31,6 @@ int snd_hdac_bus_init(struct hdac_bus *bus, struct device *dev,
 		bus->ops = ops;
 	else
 		bus->ops = &default_ops;
-	bus->io_ops = io_ops;
 	bus->dma_type = SNDRV_DMA_TYPE_DEV;
 	INIT_LIST_HEAD(&bus->stream_list);
 	INIT_LIST_HEAD(&bus->codec_list);
@@ -218,3 +215,33 @@ void snd_hdac_bus_remove_device(struct hdac_bus *bus,
 	flush_work(&bus->unsol_work);
 }
 EXPORT_SYMBOL_GPL(snd_hdac_bus_remove_device);
+
+#ifdef CONFIG_SND_HDA_ALIGNED_MMIO
+/* Helpers for aligned read/write of mmio space, for Tegra */
+unsigned int snd_hdac_aligned_read(void __iomem *addr, unsigned int mask)
+{
+	void __iomem *aligned_addr =
+		(void __iomem *)((unsigned long)(addr) & ~0x3);
+	unsigned int shift = ((unsigned long)(addr) & 0x3) << 3;
+	unsigned int v;
+
+	v = readl(aligned_addr);
+	return (v >> shift) & mask;
+}
+EXPORT_SYMBOL_GPL(snd_hdac_aligned_read);
+
+void snd_hdac_aligned_write(unsigned int val, void __iomem *addr,
+			    unsigned int mask)
+{
+	void __iomem *aligned_addr =
+		(void __iomem *)((unsigned long)(addr) & ~0x3);
+	unsigned int shift = ((unsigned long)(addr) & 0x3) << 3;
+	unsigned int v;
+
+	v = readl(aligned_addr);
+	v &= ~(mask << shift);
+	v |= val << shift;
+	writel(v, aligned_addr);
+}
+EXPORT_SYMBOL_GPL(snd_hdac_aligned_write);
+#endif /* CONFIG_SND_HDA_ALIGNED_MMIO */