Re: [PATCH 1/4] Blackfin: arch patch for 2.6.18

Arnd Bergmann
2006-09-23T13:08:01Z

On Saturday 23 September 2006 13:15, Mike Frysinger wrote:
> On 9/23/06, Arnd Bergmann <arnd@arndb.de> wrote:
> > On Saturday 23 September 2006 08:50, Mike Frysinger wrote:
> > > On 9/22/06, Arnd Bergmann <arnd@arndb.de> wrote:

> > > > What's the point, are you getting paid by lines of code? Just use
> > > > the registers directly!
> > >
> > > in our last submission we were doing exactly that ... and we were told
> > > to switch to a function style method of reading/writing memory mapped
> > > registers
> >
> > It's hard to imagine that what you have here was intended by the comment
> > then. Do you have an archive link about that discussion?
>
> no as i was not around for said discussion. but it should be in the
> threads covering the submission of blackfin for 2.6.13 ...

Ok, I found http://marc.theaimsgroup.com/?l=linux-kernel&m=114298753207549&w=2
from akpm, and I fear you heavily misunderstood him.

Your original patch had code like

/* System Reset and Interrupt Controller registers for core A (0xFFC0 0100-0xFFC0 01FF) */
#define SICA_SWRST 0xFFC00100­·····/* Software Reset register */
#define SICA_SYSCR 0xFFC00104­·····/* System Reset Configuration register */
#define SICA_RVECT 0xFFC00108­·····/* SIC Reset Vector Address Register */
#define SICA_IMASK 0xFFC0010C­·····/* SIC Interrupt Mask register 0 - hack to fix old tests */
#define SICA_IMASK0 0xFFC0010C­·····/* SIC Interrupt Mask register 0 */
#define SICA_IMASK1 0xFFC00110­·····/* SIC Interrupt Mask register 1 */
#define SICA_IAR0 0xFFC00124­·····/* SIC Interrupt Assignment Register 0 */
#define SICA_IAR1 0xFFC00128­·····/* SIC Interrupt Assignment Register 1 */
#define SICA_IAR2 0xFFC0012C­·····/* SIC Interrupt Assignment Register 2 */
#define SICA_IAR3 0xFFC00130­·····/* SIC Interrupt Assignment Register 3 */
#define SICA_IAR4 0xFFC00134­·····/* SIC Interrupt Assignment Register 4 */
#define SICA_IAR5 0xFFC00138­·····/* SIC Interrupt Assignment Register 5 */
#define SICA_IAR6 0xFFC0013C­·····/* SIC Interrupt Assignment Register 6 */
#define SICA_IAR7 0xFFC00140­·····/* SIC Interrupt Assignment Register 7 */
#define SICA_ISR0 0xFFC00114­·····/* SIC Interrupt Status register 0 */
#define SICA_ISR1 0xFFC00118­·····/* SIC Interrupt Status register 1 */
#define SICA_IWR0 0xFFC0011C­·····/* SIC Interrupt Wakeup-Enable register 0 */
#define SICA_IWR1 0xFFC00120­·····/* SIC Interrupt Wakeup-Enable register 1 */

...

#define pSICA_SWRST (volatile unsigned short *)SICA_SWRST
#define pSICA_SYSCR (volatile unsigned short *)SICA_SYSCR
#define pSICA_RVECT (volatile unsigned short *)SICA_RVECT
#define pSICA_IMASK (volatile unsigned long *)SICA_IMASK
#define pSICA_IMASK0 (volatile unsigned long *)SICA_IMASK0
#define pSICA_IMASK1 (volatile unsigned long *)SICA_IMASK1
#define pSICA_IAR0 ((volatile unsigned long *)SICA_IAR0)
#define pSICA_IAR1 (volatile unsigned long *)SICA_IAR1
#define pSICA_IAR2 (volatile unsigned long *)SICA_IAR2
#define pSICA_IAR3 (volatile unsigned long *)SICA_IAR3
#define pSICA_IAR4 (volatile unsigned long *)SICA_IAR4
#define pSICA_IAR5 (volatile unsigned long *)SICA_IAR5
#define pSICA_IAR6 (volatile unsigned long *)SICA_IAR6
#define pSICA_IAR7 (volatile unsigned long *)SICA_IAR7
#define pSICA_ISR0 (volatile unsigned long *)SICA_ISR0
#define pSICA_ISR1 (volatile unsigned long *)SICA_ISR1
#define pSICA_IWR0 (volatile unsigned long *)SICA_IWR0
#define pSICA_IWR1 (volatile unsigned long *)SICA_IWR1

static void bf561_internal_mask_irq(unsigned int irq)
{
unsigned long irq_mask;
if ((irq - (IRQ_CORETMR + 1)) < 32) {
irq_mask = (1 << (irq - (IRQ_CORETMR + 1)));
*pSICA_IMASK0 &= ~irq_mask;
} else {
irq_mask = (1 << (irq - (IRQ_CORETMR + 1) - 32));
*pSICA_IMASK1 &= ~irq_mask;
}
}

which Andrew objected to, on multiple grounds. You now converted this to

/* System Reset and Interrupt Controller registers for core A (0xFFC0 0100-0xFFC0 01FF) */
#define SICA_SWRST 0xFFC00100­·····/* Software Reset register */
#define SICA_SYSCR 0xFFC00104­·····/* System Reset Configuration register */
#define SICA_RVECT 0xFFC00108­·····/* SIC Reset Vector Address Register */
#define SICA_IMASK 0xFFC0010C­·····/* SIC Interrupt Mask register 0 - hack to fix old tests */
#define SICA_IMASK0 0xFFC0010C­·····/* SIC Interrupt Mask register 0 */
#define SICA_IMASK1 0xFFC00110­·····/* SIC Interrupt Mask register 1 */
#define SICA_IAR0 0xFFC00124­·····/* SIC Interrupt Assignment Register 0 */
#define SICA_IAR1 0xFFC00128­·····/* SIC Interrupt Assignment Register 1 */
#define SICA_IAR2 0xFFC0012C­·····/* SIC Interrupt Assignment Register 2 */
#define SICA_IAR3 0xFFC00130­·····/* SIC Interrupt Assignment Register 3 */
#define SICA_IAR4 0xFFC00134­·····/* SIC Interrupt Assignment Register 4 */
#define SICA_IAR5 0xFFC00138­·····/* SIC Interrupt Assignment Register 5 */
#define SICA_IAR6 0xFFC0013C­·····/* SIC Interrupt Assignment Register 6 */
#define SICA_IAR7 0xFFC00140­·····/* SIC Interrupt Assignment Register 7 */
#define SICA_ISR0 0xFFC00114­·····/* SIC Interrupt Status register 0 */
#define SICA_ISR1 0xFFC00118­·····/* SIC Interrupt Status register 1 */
#define SICA_IWR0 0xFFC0011C­·····/* SIC Interrupt Wakeup-Enable register 0 */
#define SICA_IWR1 0xFFC00120­·····/* SIC Interrupt Wakeup-Enable register 1 */

/* System Reset and Interrupt Controller registers for core A (0xFFC0 0100-0xFFC0 01FF) */
#define bfin_read_SICA_SWRST() bfin_read16(SICA_SWRST)
#define bfin_write_SICA_SWRST(val) bfin_write16(SICA_SWRST,val)
#define bfin_read_SICA_SYSCR() bfin_read16(SICA_SYSCR)
#define bfin_write_SICA_SYSCR(val) bfin_write16(SICA_SYSCR,val)
#define bfin_read_SICA_RVECT() bfin_read16(SICA_RVECT)
#define bfin_write_SICA_RVECT(val) bfin_write16(SICA_RVECT,val)
#define bfin_read_SICA_IMASK() bfin_read32(SICA_IMASK)
#define bfin_write_SICA_IMASK(val) bfin_write32(SICA_IMASK,val)
#define bfin_read_SICA_IMASK0() bfin_read32(SICA_IMASK0)
#define bfin_write_SICA_IMASK0(val) bfin_write32(SICA_IMASK0,val)
#define bfin_read_SICA_IMASK1() bfin_read32(SICA_IMASK1)
#define bfin_write_SICA_IMASK1(val) bfin_write32(SICA_IMASK1,val)
#define bfin_read_SICA_IAR0() bfin_read32(SICA_IAR0)
#define bfin_write_SICA_IAR0(val) bfin_write32(SICA_IAR0,val)
#define bfin_read_SICA_IAR1() bfin_read32(SICA_IAR1)
#define bfin_write_SICA_IAR1(val) bfin_write32(SICA_IAR1,val)
#define bfin_read_SICA_IAR2() bfin_read32(SICA_IAR2)
#define bfin_write_SICA_IAR2(val) bfin_write32(SICA_IAR2,val)
#define bfin_read_SICA_IAR3() bfin_read32(SICA_IAR3)
#define bfin_write_SICA_IAR3(val) bfin_write32(SICA_IAR3,val)
#define bfin_read_SICA_IAR4() bfin_read32(SICA_IAR4)
#define bfin_write_SICA_IAR4(val) bfin_write32(SICA_IAR4,val)
#define bfin_read_SICA_IAR5() bfin_read32(SICA_IAR5)
#define bfin_write_SICA_IAR5(val) bfin_write32(SICA_IAR5,val)
#define bfin_read_SICA_IAR6() bfin_read32(SICA_IAR6)
#define bfin_write_SICA_IAR6(val) bfin_write32(SICA_IAR6,val)
#define bfin_read_SICA_IAR7() bfin_read32(SICA_IAR7)
#define bfin_write_SICA_IAR7(val) bfin_write32(SICA_IAR7,val)
#define bfin_read_SICA_ISR0() bfin_read32(SICA_ISR0)
#define bfin_write_SICA_ISR0(val) bfin_write32(SICA_ISR0,val)
#define bfin_read_SICA_ISR1() bfin_read32(SICA_ISR1)
#define bfin_write_SICA_ISR1(val) bfin_write32(SICA_ISR1,val)
#define bfin_read_SICA_IWR0() bfin_read32(SICA_IWR0)
#define bfin_write_SICA_IWR0(val) bfin_write32(SICA_IWR0,val)
#define bfin_read_SICA_IWR1() bfin_read32(SICA_IWR1)
#define bfin_write_SICA_IWR1(val) bfin_write32(SICA_IWR1,val)

...
static void bf561_internal_mask_irq(unsigned int irq)
{
unsigned long irq_mask;
if ((irq - (IRQ_CORETMR + 1)) < 32) {
irq_mask = (1 << (irq - (IRQ_CORETMR + 1)));
bfin_write_SICA_IMASK0(bfin_read_SICA_IMASK0() & ~irq_mask);
} else {
irq_mask = (1 << (irq - (IRQ_CORETMR + 1) - 32));
bfin_write_SICA_IMASK1(bfin_read_SICA_IMASK1() & ~irq_mask);
}
}

which is about just as bad, but for different reasons. Now, there are
at least two common methods for how to do this better, both involving
the readl/writel low-level accessors (or something similar).

The first one uses enumerated register numers:

/* System Reset and Interrupt Controller registers for core A (0xFFC0 0100-0xFFC0 01FF) */

enum bfin_sica_regs {
SICA_SWRST = 100,­·····/* Software Reset register */
SICA_SYSCR = 104,­·····/* System Reset Configuration register */
SICA_RVECT = 108,­·····/* SIC Reset Vector Address Register */
SICA_IMASK = 10C,­·····/* SIC Interrupt Mask register 0 - hack to fix old tests */
SICA_IMASK0 = 10C,­·····/* SIC Interrupt Mask register 0 */
SICA_IMASK1 = 110,­·····/* SIC Interrupt Mask register 1 */
SICA_IAR0 = 124,­·····/* SIC Interrupt Assignment Register 0 */
SICA_IAR1 = 128,­·····/* SIC Interrupt Assignment Register 1 */
SICA_IAR2 = 12C,­·····/* SIC Interrupt Assignment Register 2 */
SICA_IAR3 = 130,­·····/* SIC Interrupt Assignment Register 3 */
SICA_IAR4 = 134,­·····/* SIC Interrupt Assignment Register 4 */
SICA_IAR5 = 138,­·····/* SIC Interrupt Assignment Register 5 */
SICA_IAR6 = 13C,­·····/* SIC Interrupt Assignment Register 6 */
SICA_IAR7 = 140,­·····/* SIC Interrupt Assignment Register 7 */
SICA_ISR0 = 114,­·····/* SIC Interrupt Status register 0 */
SICA_ISR1 = 118,­·····/* SIC Interrupt Status register 1 */
SICA_IWR0 = 11C,­·····/* SIC Interrupt Wakeup-Enable register 0 */
SICA_IWR1 = 120,­·····/* SIC Interrupt Wakeup-Enable register 1 */
};

...

static void __iomem *bfin_sica = (void __iomem *)0xffc00100ul;
static inline __le32 bfin_sica_read(int reg)
{
return (__le32)readl(bfin_sica + reg);
}

static inline void bfin_sica_write(int reg, __le32 val)
{
writel((uint32_t)val, bfin_sica + reg);
}

static void bf561_internal_mask_irq(unsigned int irq)
{
unsigned long irq_mask;
if ((irq - (IRQ_CORETMR + 1)) < 32) {
irq_mask = (1 << (irq - (IRQ_CORETMR + 1)));
bfin_sica_write(SICA_IMASK0,
bfin_sica_read(SICA_IMASK0) & ~irq_mask);
} else {
irq_mask = (1 << (irq - (IRQ_CORETMR + 1) - 32));
bfin_sica_write(SICA_IMASK0,
bfin_sica_read(SICA_IMASK0) & ~irq_mask);
}
}

The alternative approach uses a structure:

/* System Reset and Interrupt Controller registers for core A (0xFFC0 0100-0xFFC0 01FF) */

struct bfin_sica_regs {
__le32 swrst; /* Software Reset register */
__le32 syscr; /* System Reset Configuration register */
__le32 rvect; /* SIC Reset Vector Address Register */
__le32 imask[2]; /* SIC Interrupt Mask register 0-1 */
__le32 iar[8]; /* SIC Interrupt Assignment Register 0-7 */
__le32 isr[2]; /* SIC Interrupt Status register 0-1 */
__le32 iwr[2]; /* SIC Interrupt Wakeup-Enable register 0-2 */
};

...

static struct bfin_sica_regs __iomem *bfin_sica = (void __iomem *)0xffc00100ul;

static void bf561_internal_mask_irq(unsigned int irq)
{
int irqnr = irq - (IRQ_CORETMR + 1);
__le32 __iomem *reg = &bfin_sica->imask[irqnr >> 5];
unsigned long irq_mask = 1 << (irqnr & 0x1f);

writel(reg, readl(reg) & ~irq_mask);
}

I'd personally prefer the last approach because of its compactness.