From 3ebbbb56a162b8f9b9a77bc7810b9d4e0868e039 Mon Sep 17 00:00:00 2001 From: Michael Buesch Date: Fri, 19 Dec 2008 22:51:57 +0100 Subject: [PATCH] b43: Use 64bit atomic register access for TSF On modern b43 devices with core rev >=3, the hardware guarantees us an atomic 64bit read/write of the TSF, if we access the lower 32bits first. Signed-off-by: Michael Buesch Signed-off-by: John W. Linville --- drivers/net/wireless/b43/main.c | 89 +++++++++-------------------------------- 1 file changed, 20 insertions(+), 69 deletions(-) diff --git a/drivers/net/wireless/b43/main.c b/drivers/net/wireless/b43/main.c index dad0781..ba989ae 100644 --- a/drivers/net/wireless/b43/main.c +++ b/drivers/net/wireless/b43/main.c @@ -526,52 +526,20 @@ void b43_hf_write(struct b43_wldev *dev, u64 value) b43_shm_write16(dev, B43_SHM_SHARED, B43_SHM_SH_HOSTFHI, hi); } -void b43_tsf_read(struct b43_wldev *dev, u64 * tsf) +void b43_tsf_read(struct b43_wldev *dev, u64 *tsf) { - /* We need to be careful. As we read the TSF from multiple - * registers, we should take care of register overflows. - * In theory, the whole tsf read process should be atomic. - * We try to be atomic here, by restaring the read process, - * if any of the high registers changed (overflew). - */ - if (dev->dev->id.revision >= 3) { - u32 low, high, high2; - - do { - high = b43_read32(dev, B43_MMIO_REV3PLUS_TSF_HIGH); - low = b43_read32(dev, B43_MMIO_REV3PLUS_TSF_LOW); - high2 = b43_read32(dev, B43_MMIO_REV3PLUS_TSF_HIGH); - } while (unlikely(high != high2)); - - *tsf = high; - *tsf <<= 32; - *tsf |= low; - } else { - u64 tmp; - u16 v0, v1, v2, v3; - u16 test1, test2, test3; + u32 low, high; - do { - v3 = b43_read16(dev, B43_MMIO_TSF_3); - v2 = b43_read16(dev, B43_MMIO_TSF_2); - v1 = b43_read16(dev, B43_MMIO_TSF_1); - v0 = b43_read16(dev, B43_MMIO_TSF_0); + B43_WARN_ON(dev->dev->id.revision < 3); - test3 = b43_read16(dev, B43_MMIO_TSF_3); - test2 = b43_read16(dev, B43_MMIO_TSF_2); - test1 = b43_read16(dev, B43_MMIO_TSF_1); - } while (v3 != test3 || v2 != test2 || v1 != test1); + /* The hardware guarantees us an atomic read, if we + * read the low register first. */ + low = b43_read32(dev, B43_MMIO_REV3PLUS_TSF_LOW); + high = b43_read32(dev, B43_MMIO_REV3PLUS_TSF_HIGH); - *tsf = v3; - *tsf <<= 48; - tmp = v2; - tmp <<= 32; - *tsf |= tmp; - tmp = v1; - tmp <<= 16; - *tsf |= tmp; - *tsf |= v0; - } + *tsf = high; + *tsf <<= 32; + *tsf |= low; } static void b43_time_lock(struct b43_wldev *dev) @@ -598,35 +566,18 @@ static void b43_time_unlock(struct b43_wldev *dev) static void b43_tsf_write_locked(struct b43_wldev *dev, u64 tsf) { - /* Be careful with the in-progress timer. - * First zero out the low register, so we have a full - * register-overflow duration to complete the operation. - */ - if (dev->dev->id.revision >= 3) { - u32 lo = (tsf & 0x00000000FFFFFFFFULL); - u32 hi = (tsf & 0xFFFFFFFF00000000ULL) >> 32; + u32 low, high; - b43_write32(dev, B43_MMIO_REV3PLUS_TSF_LOW, 0); - mmiowb(); - b43_write32(dev, B43_MMIO_REV3PLUS_TSF_HIGH, hi); - mmiowb(); - b43_write32(dev, B43_MMIO_REV3PLUS_TSF_LOW, lo); - } else { - u16 v0 = (tsf & 0x000000000000FFFFULL); - u16 v1 = (tsf & 0x00000000FFFF0000ULL) >> 16; - u16 v2 = (tsf & 0x0000FFFF00000000ULL) >> 32; - u16 v3 = (tsf & 0xFFFF000000000000ULL) >> 48; + B43_WARN_ON(dev->dev->id.revision < 3); - b43_write16(dev, B43_MMIO_TSF_0, 0); - mmiowb(); - b43_write16(dev, B43_MMIO_TSF_3, v3); - mmiowb(); - b43_write16(dev, B43_MMIO_TSF_2, v2); - mmiowb(); - b43_write16(dev, B43_MMIO_TSF_1, v1); - mmiowb(); - b43_write16(dev, B43_MMIO_TSF_0, v0); - } + low = tsf; + high = (tsf >> 32); + /* The hardware guarantees us an atomic write, if we + * write the low register first. */ + b43_write32(dev, B43_MMIO_REV3PLUS_TSF_LOW, low); + mmiowb(); + b43_write32(dev, B43_MMIO_REV3PLUS_TSF_HIGH, high); + mmiowb(); } void b43_tsf_write(struct b43_wldev *dev, u64 tsf) -- 2.7.4