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From 64ad46379fcf14f437553f654d1adcd3d0e0d7f9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
Date: Mon, 15 Aug 2016 14:21:28 +0200
Subject: [PATCH] mtd: bcm47xxsflash: use uncached MMIO access for BCM53573
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
BCM53573 is a new series of Broadcom's SoCs. It's based on ARM and uses
this old ChipCommon-based flash access. Early tests resulted in flash
corruptions that were tracked down to using cached MMIO for flash read
access. Switch to ioremap_nocache conditionally to support BCM53573 and
don't break performance on old MIPS devices.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
---
drivers/mtd/devices/bcm47xxsflash.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
--- a/drivers/mtd/devices/bcm47xxsflash.c
+++ b/drivers/mtd/devices/bcm47xxsflash.c
@@ -296,16 +296,30 @@ static int bcm47xxsflash_bcma_probe(stru
dev_err(dev, "can't request region for resource %pR\n", res);
return -EBUSY;
}
- b47s->window = ioremap_cache(res->start, resource_size(res));
- if (!b47s->window) {
- dev_err(dev, "ioremap failed for resource %pR\n", res);
- return -ENOMEM;
- }
b47s->bcma_cc = container_of(sflash, struct bcma_drv_cc, sflash);
b47s->cc_read = bcm47xxsflash_bcma_cc_read;
b47s->cc_write = bcm47xxsflash_bcma_cc_write;
+ /*
+ * On old MIPS devices cache was magically invalidated when needed,
+ * allowing us to use cached access and gain some performance. Trying
+ * the same on ARM based BCM53573 results in flash corruptions, we need
+ * to use uncached access for it.
+ *
+ * It may be arch specific, but right now there is only 1 ARM SoC using
+ * this driver, so let's follow Broadcom's reference code and check
+ * ChipCommon revision.
+ */
+ if (b47s->bcma_cc->core->id.rev == 54)
+ b47s->window = ioremap_nocache(res->start, resource_size(res));
+ else
+ b47s->window = ioremap_cache(res->start, resource_size(res));
+ if (!b47s->window) {
+ dev_err(dev, "ioremap failed for resource %pR\n", res);
+ return -ENOMEM;
+ }
+
switch (b47s->bcma_cc->capabilities & BCMA_CC_CAP_FLASHT) {
case BCMA_CC_FLASHT_STSER:
b47s->type = BCM47XXSFLASH_TYPE_ST;
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