From e971affaf92d530b653122f08aa23e7384de170f Mon Sep 17 00:00:00 2001 From: Robert Jarzmik Date: Mon, 28 Sep 2015 22:56:51 +0200 Subject: [PATCH] mtd: nand: pxa3xx-nand: prevent DFI bus lockup on removal After the conversion of pxa architecture to common clock framework, the NAND clock can be disabled on driver exit. In this case, it happens that if the driver used the NAND and set the DFI arbitration bit, the next access to a static memory controller area, such as an ethernet card, will stall the system bus, and the core will be stalled forever. This is especially true on pxa31x SoCs, where the NDCR was augmented with a new bit to prevent this lockups by giving full ownership of the DFI arbiter to the SMC, in change SCr#6. Fix this by clearing the DFI arbritration bit in driver exit. This effectively prevents a lockup on zylonite when removing pxa3xx-nand module, and using ethernet afterwards. Signed-off-by: Robert Jarzmik Signed-off-by: Brian Norris --- drivers/mtd/nand/pxa3xx_nand.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c index da563cdd59f5..232c7074624a 100644 --- a/drivers/mtd/nand/pxa3xx_nand.c +++ b/drivers/mtd/nand/pxa3xx_nand.c @@ -76,7 +76,8 @@ #define NDCR_ND_MODE (0x3 << 21) #define NDCR_NAND_MODE (0x0) #define NDCR_CLR_PG_CNT (0x1 << 20) -#define NDCR_STOP_ON_UNCOR (0x1 << 19) +#define NFCV1_NDCR_ARB_CNTL (0x1 << 19) +#define NFCV2_NDCR_STOP_ON_UNCOR (0x1 << 19) #define NDCR_RD_ID_CNT_MASK (0x7 << 16) #define NDCR_RD_ID_CNT(x) (((x) << 16) & NDCR_RD_ID_CNT_MASK) @@ -1320,7 +1321,8 @@ static int pxa3xx_nand_detect_config(struct pxa3xx_nand_info *info) /* Set an initial chunk size */ info->chunk_size = ndcr & NDCR_PAGE_SZ ? 2048 : 512; - info->reg_ndcr = ndcr & ~NDCR_INT_MASK; + info->reg_ndcr = ndcr & + ~(NDCR_INT_MASK | NDCR_ND_ARB_EN | NFCV1_NDCR_ARB_CNTL); info->ndtr0cs0 = nand_readl(info, NDTR0CS0); info->ndtr1cs0 = nand_readl(info, NDTR1CS0); return 0; @@ -1553,6 +1555,7 @@ static int pxa3xx_nand_scan(struct mtd_info *mtd) pxa3xx_flash_ids[1].name = NULL; def = pxa3xx_flash_ids; KEEP_CONFIG: + info->reg_ndcr |= (pdata->enable_arbiter) ? NDCR_ND_ARB_EN : 0; if (info->reg_ndcr & NDCR_DWIDTH_M) chip->options |= NAND_BUSWIDTH_16; @@ -1768,6 +1771,16 @@ static int pxa3xx_nand_remove(struct platform_device *pdev) free_irq(irq, info); pxa3xx_nand_free_buff(info); + /* + * In the pxa3xx case, the DFI bus is shared between the SMC and NFC. + * In order to prevent a lockup of the system bus, the DFI bus + * arbitration is granted to SMC upon driver removal. This is done by + * setting the x_ARB_CNTL bit, which also prevents the NAND to have + * access to the bus anymore. + */ + nand_writel(info, NDCR, + (nand_readl(info, NDCR) & ~NDCR_ND_ARB_EN) | + NFCV1_NDCR_ARB_CNTL); clk_disable_unprepare(info->clk); for (cs = 0; cs < pdata->num_cs; cs++) -- 2.20.1