Re: [PATCH 6/8] [POWERPC] sysdev,qe_lib: implement FSL GTM support

[Anton Vorontsov]

On Thu, Apr 17, 2008 at 04:23:56PM +0200, Laurent Pinchart wrote:
> > +   /*
> > +    * We have two 8 bit prescalers -- primary and secondary (psr, sps),
> > +    * plus "slow go" mode (clk / 16). So, total prescale value is
> > +    * 16 * (psr + 1) * (sps + 1).
> > +    */
> > +   if (prescaler > 256 * 256 * 16)
> > +           return -EINVAL;
> > +
> > +   if (prescaler > 256 * 256) {
> > +           iclk = GTMDR_ICLK_SLGO;
> > +           prescaler /= 16;
> > +   }
> > +
> > +   if (prescaler > 256) {
> > +           psr = 256 - 1;
> > +           sps = prescaler / 256 - 1;
> > +   } else {
> > +           psr = prescaler - 1;
> > +           sps = 1 - 1;
> > +   }
> 
> Don't forget that the CPM2 doesn't support the primary prescaler.

Here is incremental diff of how this is solved. I guess this should work.

diff --git a/Documentation/powerpc/booting-without-of.txt 
b/Documentation/powerpc/booting-without-of.txt
index b0ddd54..b89c56d 100644
--- a/Documentation/powerpc/booting-without-of.txt
+++ b/Documentation/powerpc/booting-without-of.txt
@@ -2835,7 +2835,7 @@ platforms are moved over to use the flattened-device-tree 
model.
 
     Required properties:
       - compatible : should be "fsl,gtm" ("fsl,qe-gtm" in addition for QE
-                     GTMs).
+                     GTMs or "fsl,cpm2-gtm" for CPM2 GTMs).
       - reg : should contain gtm registers location and length (0x40).
       - interrupts : should contain four interrupts.
       - interrupt-parent : interrupt source phandle.
diff --git a/arch/powerpc/sysdev/fsl_gtm.c b/arch/powerpc/sysdev/fsl_gtm.c
index 6d86983..105c633 100644
--- a/arch/powerpc/sysdev/fsl_gtm.c
+++ b/arch/powerpc/sysdev/fsl_gtm.c
@@ -125,27 +125,32 @@ static int gtm_reset_ref_timer16(struct gtm_timer *tmr, 
int frequency,
        u8 psr;
        u8 sps;
        unsigned long flags;
+       int max_prescaler = 256 * 256 * 16;
+
+       /* CPM2 doesn't have primary prescaler */
+       if (!tmr->gtpsr)
+               max_prescaler /= 256;
 
        prescaler = gtm->clock / frequency;
        /*
         * We have two 8 bit prescalers -- primary and secondary (psr, sps),
         * plus "slow go" mode (clk / 16). So, total prescale value is
-        * 16 * (psr + 1) * (sps + 1).
+        * 16 * (psr + 1) * (sps + 1). Though, for CPM2 GTMs we losing psr.
         */
-       if (prescaler > 256 * 256 * 16)
+       if (prescaler > max_prescaler)
                return -EINVAL;
 
-       if (prescaler > 256 * 256) {
+       if (prescaler > max_prescaler / 16) {
                iclk = GTMDR_ICLK_SLGO;
                prescaler /= 16;
        }
 
-       if (prescaler > 256) {
+       if (prescaler <= 256) {
+               psr = 0;
+               sps = prescaler - 1;
+       } else {
                psr = 256 - 1;
                sps = prescaler / 256 - 1;
-       } else {
-               psr = prescaler - 1;
-               sps = 1 - 1;
        }
 
        spin_lock_irqsave(&gtm->lock, flags);
@@ -159,7 +164,8 @@ static int gtm_reset_ref_timer16(struct gtm_timer *tmr, int 
frequency,
 
        setbits8(tmr->gtcfr, GTCFR_STP(num));
 
-       out_be16(tmr->gtpsr, psr);
+       if (tmr->gtpsr)
+               out_be16(tmr->gtpsr, psr);
        clrsetbits_be16(tmr->gtmdr, 0xFFFF, iclk | GTMDR_SPS(sps) |
                        GTMDR_ORI | (free_run ? GTMDR_FFR : 0));
        out_be16(tmr->gtcnr, 0);
@@ -222,7 +228,8 @@ void gtm_stop_timer16(struct gtm_timer *tmr)
 }
 EXPORT_SYMBOL(gtm_stop_timer16);
 
-static void __init gtm_set_shortcuts(struct gtm_timer *timers,
+static void __init gtm_set_shortcuts(struct device_node *np,
+                                    struct gtm_timer *timers,
                                     struct gtm_timers_regs __iomem *regs)
 {
        /*
@@ -233,31 +240,35 @@ static void __init gtm_set_shortcuts(struct gtm_timer 
*timers,
         */
        timers[0].gtcfr = &regs->gtcfr1;
        timers[0].gtmdr = &regs->gtmdr1;
-       timers[0].gtpsr = &regs->gtpsr1;
        timers[0].gtcnr = &regs->gtcnr1;
        timers[0].gtrfr = &regs->gtrfr1;
        timers[0].gtevr = &regs->gtevr1;
 
        timers[1].gtcfr = &regs->gtcfr1;
        timers[1].gtmdr = &regs->gtmdr2;
-       timers[1].gtpsr = &regs->gtpsr2;
        timers[1].gtcnr = &regs->gtcnr2;
        timers[1].gtrfr = &regs->gtrfr2;
        timers[1].gtevr = &regs->gtevr2;
 
        timers[2].gtcfr = &regs->gtcfr2;
        timers[2].gtmdr = &regs->gtmdr3;
-       timers[2].gtpsr = &regs->gtpsr3;
        timers[2].gtcnr = &regs->gtcnr3;
        timers[2].gtrfr = &regs->gtrfr3;
        timers[2].gtevr = &regs->gtevr3;
 
        timers[3].gtcfr = &regs->gtcfr2;
        timers[3].gtmdr = &regs->gtmdr4;
-       timers[3].gtpsr = &regs->gtpsr4;
        timers[3].gtcnr = &regs->gtcnr4;
        timers[3].gtrfr = &regs->gtrfr4;
        timers[3].gtevr = &regs->gtevr4;
+
+       /* CPM2 doesn't have primary prescaler */
+       if (!of_device_is_compatible(np, "fsl,cpm2-gtm")) {
+               timers[0].gtpsr = &regs->gtpsr1;
+               timers[1].gtpsr = &regs->gtpsr2;
+               timers[2].gtpsr = &regs->gtpsr3;
+               timers[3].gtpsr = &regs->gtpsr4;
+       }
 }
 
 static int __init gtm_init(void)
@@ -307,7 +318,7 @@ static int __init gtm_init(void)
                        goto err;
                }
 
-               gtm_set_shortcuts(gtm->timers, gtm->regs);
+               gtm_set_shortcuts(np, gtm->timers, gtm->regs);
 
                /* We don't want to lose the node and its ->data */
                of_node_get(np);
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