Add bridged amplifiers to cs42l43

Merge series from Charles Keepax <ckeepax@opensource.cirrus.com>:

In some cs42l43 systems a couple of cs35l56 amplifiers are attached
to the cs42l43's SPI and I2S. On Windows the cs42l43 is controlled
by a SDCA class driver and these two amplifiers are controlled by
firmware running on the cs42l43. However, under Linux the decision
was made to interact with the cs42l43 directly, affording the user
greater control over the audio system. However, this has resulted
in an issue where these two bridged cs35l56 amplifiers are not
populated in ACPI and must be added manually. There is at least an
SDCA extension unit DT entry we can key off.

The process of adding this is handled using a software node, firstly the
ability to add native chip selects to software nodes must be added.
Secondly, an additional flag for naming the SPI devices is added this
allows the machine driver to key to the correct amplifier. Then finally,
the cs42l43 SPI driver adds the two amplifiers directly onto its SPI
bus.

An additional series will follow soon to add the audio machine driver
parts (in the sof-sdw driver), however that is fairly orthogonal to
this part of the process, getting the actual amplifiers registered.

1 files changed, 18 insertions, 7 deletions

diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c
index 86571e760dd61..343c3456c8ddf 100644
--- a/kernel/bpf/arena.c
+++ b/kernel/bpf/arena.c
@@ -38,7 +38,7 @@
 
 /* number of bytes addressable by LDX/STX insn with 16-bit 'off' field */
 #define GUARD_SZ (1ull << sizeof(((struct bpf_insn *)0)->off) * 8)
-#define KERN_VM_SZ ((1ull << 32) + GUARD_SZ)
+#define KERN_VM_SZ (SZ_4G + GUARD_SZ)
 
 struct bpf_arena {
 	struct bpf_map map;
@@ -110,7 +110,7 @@ static struct bpf_map *arena_map_alloc(union bpf_attr *attr)
 		return ERR_PTR(-EINVAL);
 
 	vm_range = (u64)attr->max_entries * PAGE_SIZE;
-	if (vm_range > (1ull << 32))
+	if (vm_range > SZ_4G)
 		return ERR_PTR(-E2BIG);
 
 	if ((attr->map_extra >> 32) != ((attr->map_extra + vm_range - 1) >> 32))
@@ -301,7 +301,7 @@ static unsigned long arena_get_unmapped_area(struct file *filp, unsigned long ad
 
 	if (pgoff)
 		return -EINVAL;
-	if (len > (1ull << 32))
+	if (len > SZ_4G)
 		return -E2BIG;
 
 	/* if user_vm_start was specified at arena creation time */
@@ -322,7 +322,7 @@ static unsigned long arena_get_unmapped_area(struct file *filp, unsigned long ad
 	if (WARN_ON_ONCE(arena->user_vm_start))
 		/* checks at map creation time should prevent this */
 		return -EFAULT;
-	return round_up(ret, 1ull << 32);
+	return round_up(ret, SZ_4G);
 }
 
 static int arena_map_mmap(struct bpf_map *map, struct vm_area_struct *vma)
@@ -346,7 +346,7 @@ static int arena_map_mmap(struct bpf_map *map, struct vm_area_struct *vma)
 		return -EBUSY;
 
 	/* Earlier checks should prevent this */
-	if (WARN_ON_ONCE(vma->vm_end - vma->vm_start > (1ull << 32) || vma->vm_pgoff))
+	if (WARN_ON_ONCE(vma->vm_end - vma->vm_start > SZ_4G || vma->vm_pgoff))
 		return -EFAULT;
 
 	if (remember_vma(arena, vma))
@@ -420,7 +420,7 @@ static long arena_alloc_pages(struct bpf_arena *arena, long uaddr, long page_cnt
 		if (uaddr & ~PAGE_MASK)
 			return 0;
 		pgoff = compute_pgoff(arena, uaddr);
-		if (pgoff + page_cnt > page_cnt_max)
+		if (pgoff > page_cnt_max - page_cnt)
 			/* requested address will be outside of user VMA */
 			return 0;
 	}
@@ -447,7 +447,13 @@ static long arena_alloc_pages(struct bpf_arena *arena, long uaddr, long page_cnt
 		goto out;
 
 	uaddr32 = (u32)(arena->user_vm_start + pgoff * PAGE_SIZE);
-	/* Earlier checks make sure that uaddr32 + page_cnt * PAGE_SIZE will not overflow 32-bit */
+	/* Earlier checks made sure that uaddr32 + page_cnt * PAGE_SIZE - 1
+	 * will not overflow 32-bit. Lower 32-bit need to represent
+	 * contiguous user address range.
+	 * Map these pages at kern_vm_start base.
+	 * kern_vm_start + uaddr32 + page_cnt * PAGE_SIZE - 1 can overflow
+	 * lower 32-bit and it's ok.
+	 */
 	ret = vm_area_map_pages(arena->kern_vm, kern_vm_start + uaddr32,
 				kern_vm_start + uaddr32 + page_cnt * PAGE_SIZE, pages);
 	if (ret) {
@@ -510,6 +516,11 @@ static void arena_free_pages(struct bpf_arena *arena, long uaddr, long page_cnt)
 		if (!page)
 			continue;
 		if (page_cnt == 1 && page_mapped(page)) /* mapped by some user process */
+			/* Optimization for the common case of page_cnt==1:
+			 * If page wasn't mapped into some user vma there
+			 * is no need to call zap_pages which is slow. When
+			 * page_cnt is big it's faster to do the batched zap.
+			 */
 			zap_pages(arena, full_uaddr, 1);
 		vm_area_unmap_pages(arena->kern_vm, kaddr, kaddr + PAGE_SIZE);
 		__free_page(page);