[PATCH v4 2/2] ARM: cache-l2x0: optimize aurora range operations

Arnd Bergmann
2014-11-19T16:00:21Z

The aurora_inv_range(), aurora_clean_range() and aurora_flush_range()
functions are highly redundant, both in source and in object code, and
they are harder to understand than necessary.

By moving the range loop into the aurora_pa_range() function, they
become trivial wrappers, and the object code start looking like what
one would expect for an optimal implementation.

Further optimization may be possible by using the per-CPU "virtual"
registers to avoid the spinlocks in most cases.

Reviewed-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
(on Armada 370 RD and Armada XP GP, boot tested, plus a little bit of
DMA traffic by reading data from a SD card)
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
index 341ba8aaca42..e2013b9c4362 100644
--- a/arch/arm/mm/cache-l2x0.c
+++ b/arch/arm/mm/cache-l2x0.c
@@ -1164,7 +1164,7 @@ static const struct l2c_init_data of_l2c310_coherent_data __initconst = {
* noninclusive, while the hardware cache range operations use
* inclusive start and end addresses.
*/
-static unsigned long calc_range_end(unsigned long start, unsigned long end)
+static unsigned long aurora_range_end(unsigned long start, unsigned long end)
{
/*
* Limit the number of cache lines processed at once,
@@ -1183,26 +1183,13 @@ static unsigned long calc_range_end(unsigned long start, unsigned long end)
return end;
}

-/*
- * Make sure 'start' and 'end' reference the same page, as L2 is PIPT
- * and range operations only do a TLB lookup on the start address.
- */
static void aurora_pa_range(unsigned long start, unsigned long end,
- unsigned long offset)
+ unsigned long offset)
{
void __iomem *base = l2x0_base;
+ unsigned long range_end;
unsigned long flags;

- raw_spin_lock_irqsave(&l2x0_lock, flags);
- writel_relaxed(start, base + AURORA_RANGE_BASE_ADDR_REG);
- writel_relaxed(end, base + offset);
- raw_spin_unlock_irqrestore(&l2x0_lock, flags);
-
- writel_relaxed(0, base + AURORA_SYNC_REG);
-}
-
-static void aurora_inv_range(unsigned long start, unsigned long end)
-{
/*
* round start and end adresses up to cache line size
*/
@@ -1210,15 +1197,24 @@ static void aurora_inv_range(unsigned long start, unsigned long end)
end = ALIGN(end, CACHE_LINE_SIZE);

/*
- * Invalidate all full cache lines between 'start' and 'end'.
+ * perform operation on all full cache lines between 'start' and 'end'
*/
while (start < end) {
- unsigned long range_end = calc_range_end(start, end);
- aurora_pa_range(start, range_end - CACHE_LINE_SIZE,
- AURORA_INVAL_RANGE_REG);
+ range_end = aurora_range_end(start, end);
+
+ raw_spin_lock_irqsave(&l2x0_lock, flags);
+ writel_relaxed(start, base + AURORA_RANGE_BASE_ADDR_REG);
+ writel_relaxed(range_end - CACHE_LINE_SIZE, base + offset);
+ raw_spin_unlock_irqrestore(&l2x0_lock, flags);
+
+ writel_relaxed(0, base + AURORA_SYNC_REG);
start = range_end;
}
}
+static void aurora_inv_range(unsigned long start, unsigned long end)
+{
+ aurora_pa_range(start, end, AURORA_INVAL_RANGE_REG);
+}

static void aurora_clean_range(unsigned long start, unsigned long end)
{
@@ -1226,36 +1222,16 @@ static void aurora_clean_range(unsigned long start, unsigned long end)
* If L2 is forced to WT, the L2 will always be clean and we
* don't need to do anything here.
*/
- if (!l2_wt_override) {
- start &= ~(CACHE_LINE_SIZE - 1);
- end = ALIGN(end, CACHE_LINE_SIZE);
- while (start != end) {
- unsigned long range_end = calc_range_end(start, end);
- aurora_pa_range(start, range_end - CACHE_LINE_SIZE,
- AURORA_CLEAN_RANGE_REG);
- start = range_end;
- }
- }
+ if (!l2_wt_override)
+ aurora_pa_range(start, end, AURORA_CLEAN_RANGE_REG);
}

static void aurora_flush_range(unsigned long start, unsigned long end)
{
- start &= ~(CACHE_LINE_SIZE - 1);
- end = ALIGN(end, CACHE_LINE_SIZE);
- while (start != end) {
- unsigned long range_end = calc_range_end(start, end);
- /*
- * If L2 is forced to WT, the L2 will always be clean and we
- * just need to invalidate.
- */
- if (l2_wt_override)
- aurora_pa_range(start, range_end - CACHE_LINE_SIZE,
- AURORA_INVAL_RANGE_REG);
- else
- aurora_pa_range(start, range_end - CACHE_LINE_SIZE,
- AURORA_FLUSH_RANGE_REG);
- start = range_end;
- }
+ if (l2_wt_override)
+ aurora_pa_range(start, end, AURORA_INVAL_RANGE_REG);
+ else
+ aurora_pa_range(start, end, AURORA_FLUSH_RANGE_REG);
}

static void aurora_flush_all(void)