Question regarding mpic_assign_isu() in storcenter.c

Question regarding mpic_assign_isu() in storcenter.c

[Eric Witcher]

Can anyone explain why the comment preceding mpic_assign_isu() on line 145 says that the I2C registers are at 0x11020 yet the code on line 146 shows 0x11000?

The MPC8245 user manual shows the external interrupt 0 registers at 0x10200 (paddr=40000) and the I2C registers at 0x11020.


<from storcenter.c> <2.6.25.6>

/*
 112 * Interrupt setup and service.  Interrrupts on the turbostation come
 113 * from the four PCI slots plus onboard 8241 devices: I2C, DUART.
 114 */
 115static void __init storcenter_init_IRQ(void)
 116{
 117        struct mpic *mpic;
 118        struct device_node *dnp;
 119        const void *prop;
 120        int size;
 121        phys_addr_t paddr;
 122
 123        dnp = of_find_node_by_type(NULL, "open-pic");
 124        if (dnp == NULL)
 125                return;
 126
 127        prop = of_get_property(dnp, "reg", &size);
 128        if (prop == NULL) {
 129                of_node_put(dnp);
 130                return;
 131        }
 132
 133        paddr = (phys_addr_t)of_translate_address(dnp, prop);
 134        mpic = mpic_alloc(dnp, paddr, MPIC_PRIMARY | MPIC_WANTS_RESET,
 135                        16, 32, " OpenPIC  ");
 136
 137        of_node_put(dnp);
 138
 139        BUG_ON(mpic == NULL);
 140
 141        /*
 142         * 16 Serial Interrupts followed by 16 Internal Interrupts.
 143         * I2C is the second internal, so it is at 17, 0x11020.
 144         */
 145        mpic_assign_isu(mpic, 0, paddr + 0x10200);
 146        mpic_assign_isu(mpic, 1, paddr + 0x11000);
 147
 148        mpic_init(mpic);
 149}

Re: Question regarding mpic_assign_isu() in storcenter.c

[Eric Witcher]

The answer is that mpic_assign_isu(mpic, 1, paddr + 0x11000) places the initial base register
for isu 1 on a reserved location in the PIC register map (see *).  I guess you can infer from this
that no badness occurs when you write to a reserved location on the PIC.

That aside, when you walk through mpic_init(), the resulting vector placement as a result of
the mpic_assign_isu() calls are consistent with the corresponding device tree.

isu     vector     register_offset     pic           device_tree (storecenter.dts)
0       0          0x10200             INT0/Serial 0
0       1          0x10220             INT1/Serial 1
0       2          0x10240             INT2/Serial 2
0       3          0x10260             INT3/Serial 3
0       4          0x10280             INT4/Serial 4
0       5          0x102A0             Serial 5
0       6          0x102C0             Serial 6
0       7          0x102E0             Serial 7
0       8          0x10300             Serial 8
0       9          0x10320             Serial 9
0       10         0x10340             Serial 10
0       11         0x10360             Serial 11
0       12         0x10380             Serial 12
0       13         0x103A0             Serial 13
0       14         0x103C0             Serial 14
0       15         0x103E0             Serial 15

1       16         0x11000             Reserved*
1       17         0x11020             I2C           i2c@3000
1       18         0x11040             DMA 0
1       19         0x11060             DMA 1
1       20         0x11080             Reserved
1       21         0x110A0             Reserved
1       22         0x110C0             Message unit
1       23         0x110E0             Reserved 
1       24         0x11100             Reserved
1       25         0x11120             DUART 1       serial0
1       26         0x11140             DUART 2       serial1
1       27         0x11160             Reserved
1       28         0x11180             Reserved
1       29         0x111A0             Reserved
1       30         0x111C0             Reserved
1       31         0x111E0             Reserved

Re: Question regarding mpic_assign_isu() in storcenter.c

[Jon Loeliger]

Eric Witcher wrote:
> The answer is that mpic_assign_isu(mpic, 1, paddr + 0x11000) places the initial base register
> for isu 1 on a reserved location in the PIC register map (see *).  I guess you can infer from this
> that no badness occurs when you write to a reserved location on the PIC.

See?  See Kumar?  Didn't you tell me that would
come back to haunt us juuust like you said... :-)

jdl

Re: Question regarding mpic_assign_isu() in storcenter.c

[Kumar Gala]

On Jun 18, 2008, at 11:10 AM, Jon Loeliger wrote:

> Eric Witcher wrote:
>> The answer is that mpic_assign_isu(mpic, 1, paddr + 0x11000) places  
>> the initial base register
>> for isu 1 on a reserved location in the PIC register map (see *).   
>> I guess you can infer from this
>> that no badness occurs when you write to a reserved location on the  
>> PIC.
>
> See?  See Kumar?  Didn't you tell me that would
> come back to haunt us juuust like you said... :-)

I feel like I remember saying something about that :)

I've submitted a patch to deal with the issue so we can just use 256  
and remove all the multiple isu business.

- k