Re: [PATCH] edac: mpc85xx: add support for mpc83xx memory controller

On Wed, Jul 08, 2009 at 01:09:39PM -0500, Kumar Gala wrote:

On Jul 8, 2009, at 11:19 AM, Ira W. Snyder wrote:

quoted

Add support for the Freescale MPC83xx memory controller to the  
existing
driver for the Freescale MPC85xx memory controller. The only  
difference
between the two processors are in the CS_BNDS register parsing code.

The L2 cache controller does not exist on the MPC83xx, but the OF  
subsystem
will not use the driver if the device is not present in the OF device 
tree.

Signed-off-by: Ira W. Snyder <redacted>
---

This was tested on an MPC8349EMDS-based board.

I don't really like how the MCE disable works on mpc85xx (clearing the
HID1 register), but this can be revisited when mpc86xx support gets
added. It sucks to have this happen before the probe() routine is  
called
and we know what kind of hardware we're actually running on.

drivers/edac/Kconfig        |    6 +++---
drivers/edac/mpc85xx_edac.c |   38 +++++++++++++++++++++++++++ 
+----------
drivers/edac/mpc85xx_edac.h |    3 +++
3 files changed, 34 insertions(+), 13 deletions(-)

[snip]

quoted

/************************ MC SYSFS parts  
***********************************/

@@ -738,7 +740,8 @@ static irqreturn_t mpc85xx_mc_isr(int irq, void  

*dev_id)
	return IRQ_HANDLED;
}

-static void __devinit mpc85xx_init_csrows(struct mem_ctl_info *mci)
+static void __devinit mpc85xx_init_csrows(struct mem_ctl_info *mci,
+					  const struct of_device_id *match)
{
	struct mpc85xx_mc_pdata *pdata = mci->pvt_info;
	struct csrow_info *csrow;

@@ -784,18 +787,26 @@ static void __devinit mpc85xx_init_csrows(struct 

mem_ctl_info *mci)
	}

	for (index = 0; index < mci->nr_csrows; index++) {
-		u32 start;
-		u32 end;
+		u32 start, end, extra;

		csrow = &mci->csrows[index];
		cs_bnds = in_be32(pdata->mc_vbase + MPC85XX_MC_CS_BNDS_0 +
				  (index * MPC85XX_MC_CS_BNDS_OFS));
-		start = (cs_bnds & 0xfff0000) << 4;
-		end = ((cs_bnds & 0xfff) << 20);
+
+		if (match->data && match->data == MPC83xx) {
+			start = (cs_bnds & 0x00ff0000) << 8;
+			end   = (cs_bnds & 0x000000ff) << 24;
+			extra = 0x00ffffff;
+		} else {
+			start = (cs_bnds & 0x0fff0000) << 4;
+			end   = (cs_bnds & 0x00000fff) << 20;
+			extra = 0x000fffff;
+		}

I don't understand this at all.. The only difference between 83xx & 85xx 
is that we should have an extra 4-bits for 36-bit physical addresses.

We should be able to write this code in such a way that it works for  
both 83xx & 85xx.

                start = (cs_bnds & 0xffff0000) >> 16;
                end = (cs_bnds & 0xffff);

		if (start == end)
			continue;
		start <<= (20 - PAGE_SHIFT);
		end <<= (20 - PAGE_SHIFT);
		end |= (1 << (20 - PAGE_SHIFT)) - 1;

Sorry, I don't know a thing about PAGE_SHIFT. Looking in
arch/powerpc/platforms/Kconfig.cputype, PPC_85xx doesn't seem to imply a
change in PAGE_SIZE, which changes the PAGE_SHIFT in
arch/powerpc/include/asm/page.h.

Also, are you sure you cannot use 4K pages on an 85xx? If you can use 4K
pages on 85xx, then PAGE_SHIFT == 12, and your solution breaks.

I admit I don't know much about all of the different powerpc platforms.

Ira