[PATCH 1/9] dma: pl330: rip out broken, redundant ID probing

[Will Deacon]

The PL330 driver probes the peripheral and primecell IDs of the device to
make sure that it is indeed an AMBA PL330. However, it does this by
making byte accesses to a device mapping of the word-aligned ID
registers, which is either UNPREDICTABLE or generates an alignment fault
(depending on the presence of the virtualisation extensions).

Rather than fix this code, we can actually rip most of it out and let
the AMBA bus driver correctly do the probing for us.

Cc: Jassi Brar <jaswinder.singh at linaro.org>
Cc: Vinod Koul <vinod.koul at intel.com>
Signed-off-by: Will Deacon <will.deacon at arm.com>
---
 drivers/dma/pl330.c | 27 +++------------------------
 1 file changed, 3 insertions(+), 24 deletions(-)

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index 24e0754..22e2a8f 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -157,7 +157,6 @@ enum pl330_reqtype {
 #define PERIPH_REV_R0P0		0
 #define PERIPH_REV_R1P0		1
 #define PERIPH_REV_R1P1		2
-#define PCELL_ID		0xff0
 
 #define CR0_PERIPH_REQ_SET	(1 << 0)
 #define CR0_BOOT_EN_SET		(1 << 1)
@@ -193,8 +192,6 @@ enum pl330_reqtype {
 #define INTEG_CFG		0x0
 #define PERIPH_ID_VAL		((PART << 0) | (DESIGNER << 12))
 
-#define PCELL_ID_VAL		0xb105f00d
-
 #define PL330_STATE_STOPPED		(1 << 0)
 #define PL330_STATE_EXECUTING		(1 << 1)
 #define PL330_STATE_WFE			(1 << 2)
@@ -292,7 +289,6 @@ static unsigned cmd_line;
 /* Populated by the PL330 core driver for DMA API driver's info */
 struct pl330_config {
 	u32	periph_id;
-	u32	pcell_id;
 #define DMAC_MODE_NS	(1 << 0)
 	unsigned int	mode;
 	unsigned int	data_bus_width:10; /* In number of bits */
@@ -650,19 +646,6 @@ static inline bool _manager_ns(struct pl330_thread *thrd)
 	return (pl330->pinfo->pcfg.mode & DMAC_MODE_NS) ? true : false;
 }
 
-static inline u32 get_id(struct pl330_info *pi, u32 off)
-{
-	void __iomem *regs = pi->base;
-	u32 id = 0;
-
-	id |= (readb(regs + off + 0x0) << 0);
-	id |= (readb(regs + off + 0x4) << 8);
-	id |= (readb(regs + off + 0x8) << 16);
-	id |= (readb(regs + off + 0xc) << 24);
-
-	return id;
-}
-
 static inline u32 get_revision(u32 periph_id)
 {
 	return (periph_id >> PERIPH_REV_SHIFT) & PERIPH_REV_MASK;
@@ -1986,9 +1969,6 @@ static void read_dmac_config(struct pl330_info *pi)
 	pi->pcfg.num_events = val;
 
 	pi->pcfg.irq_ns = readl(regs + CR3);
-
-	pi->pcfg.periph_id = get_id(pi, PERIPH_ID);
-	pi->pcfg.pcell_id = get_id(pi, PCELL_ID);
 }
 
 static inline void _reset_thread(struct pl330_thread *thrd)
@@ -2098,10 +2078,8 @@ static int pl330_add(struct pl330_info *pi)
 	regs = pi->base;
 
 	/* Check if we can handle this DMAC */
-	if ((get_id(pi, PERIPH_ID) & 0xfffff) != PERIPH_ID_VAL
-	   || get_id(pi, PCELL_ID) != PCELL_ID_VAL) {
-		dev_err(pi->dev, "PERIPH_ID 0x%x, PCELL_ID 0x%x !\n",
-			get_id(pi, PERIPH_ID), get_id(pi, PCELL_ID));
+	if ((pi->pcfg.periph_id & 0xfffff) != PERIPH_ID_VAL) {
+		dev_err(pi->dev, "PERIPH_ID 0x%x !\n", pi->pcfg.periph_id);
 		return -EINVAL;
 	}
 
@@ -2922,6 +2900,7 @@ pl330_probe(struct amba_device *adev, const struct amba_id *id)
 	if (ret)
 		return ret;
 
+	pi->pcfg.periph_id = adev->periphid;
 	ret = pl330_add(pi);
 	if (ret)
 		goto probe_err1;
-- 
1.8.2.2