Subject: Re: Problem reading and programming memory location...

From: Anatolij Gustschin <[email-masked]>
Date: Sat, 16 Nov 2013 15:29:33 +0100

Hi Lorenzo,

see my comments below.

On Fri, 15 Nov 2013 17:27:30 +0100
neorf3k <[email-masked]> wrote:

> Hello again, I’ve tried this code, but we are not able to
> change cs4 reg value… what could be?
> 
> —
> 
> #define MALab_DEVICE_NAME	"MALab"
> #define MPC5xxx_MM_CS4_START	(MBAR_BASE + 0x0024)
> #define MPC5xxx_MM_CS4_STOP	(MBAR_BASE + 0x0028)
> #define MPC5xxx_MM_IPBI	 (MBAR_BASE + 0x0054)
> 
> #define MALab_MM_START	 0x10020000U
> #define MALab_MM_END	 0x10020FFFU

Please change MALab_MM_END to 0x10030000U.

> #define MALab_MM_SIZE	 0x00001000U
> 
> int init_module(void) { ...
>     u16 cs4_start_value;
>     u16 cs4_stop_value;
>     u32 cs4_enable_value;
>     
>     u8 rvoice_ioaddr_value;
> 
>     
>     // reserve a page of memory for our hardware /proc/iomem
>     if ( check_region(MALab_MM_START,MALab_MM_SIZE) ) {
>         printk (KERN_ALERT "LED init_module: memory already in use\n");
>         return -EBUSY;
>     }
> 
>     
>     request_mem_region(MALab_MM_START,MALab_MM_SIZE,MALab_DEVICE_NAME);
> 
>     
>     void __iomem *cs0_reg   = ioremap ((volatile unsigned long)(MBAR_BASE + 0x0300), 4);
>     void __iomem *cs3_reg   = ioremap ((volatile unsigned long)(MBAR_BASE + 0x030C), 4);
>
>     void __iomem *ipbi_cr = ioremap ((volatile unsigned long)(MPC5xxx_MM_IPBI), 4);
>     void __iomem *cs4_start  = ioremap ((volatile unsigned long)(MPC5xxx_MM_CS4_START + 2), 2);
>     void __iomem *cs4_stop   = ioremap ((volatile unsigned long)(MPC5xxx_MM_CS4_STOP + 2), 2);
>     
>     void __iomem *cs4_enable   = ioremap ((volatile unsigned long)(MBAR_BASE + 0x0310), 4);
>     void __iomem *cs_ctrl_reg   = ioremap ((volatile unsigned long)(MBAR_BASE + 0x0318), 4);

this might work, but this is not how ioremap() supposed to be used.
The mapping is done in 4k-page granularity, so it would be better
to just map the internal register range my one ioremap() call, i.e.

    reg_base = ioremap(MBAR_BASE, 0x400);

and then to calculate the register offsets, i.e.

   cs0_reg = reg_base + 0x0300;
   cs0_reg = reg_base + 0x030C;
   ...
   ipbi_cr = reg_base + 0x0054;
   cs4_start = reg_base + 0x0026;
   cs4_stop = reg_base + 0x002a;
   ...

For FPGA mapping you need a separate ioremap() call of course.

>     void __iomem *rvoice_ioaddr   = ioremap ((volatile unsigned long)(MALab_MM_START), MALab_MM_SIZE);
>
>     //disable CSO
> 
>     out_be32(cs0_reg, 0x0004ed00);
> 
>     
>     //disable CS3
> 
>     out_be32(cs3_reg, 0x0002cf00);
> 
>     // enable LocalBus chip select CS4
>     out_be32(ipbi_cr, 0x00290001);

The comment and the code doesn't match here, the code disables
CS4 to configure the its range, so the comment is confusing.

>     cs4_start_value=in_be16(cs4_start);
>     cs4_start_value=MALab_MM_START >>16;
>     out_be16(cs4_start, cs4_start_value);
>     cs4_stop_value=in_be16(cs4_stop);
>     cs4_stop_value=MALab_MM_END >>16;
>     out_be16(cs4_stop, cs4_stop_value);

Here is the problem. The _minimal_ chip select range _must_
be 64 KiB, otherwise the register access can't work. Your
current chip select 4 range is less then 1 KiB:

  0x10020FFF - 0x10020000 = 0xFFF

Since you right-shift the start and stop values by 16,
the chip select start and stop registers are both 0x1002.
The resulting chip select address range is 0. Therefore
please set MALab_MM_END value to 0x10030000.

Thanks,
Anatolij