[RFC V2 5/8] ARM i.MX: clk: add generic support of gate2b

[Richard Zhao]

On Fri, Dec 16, 2011 at 03:25:53PM -0800, Mike Turquette wrote:
> On Wed, Dec 14, 2011 at 1:23 AM, Richard Zhao <richard.zhao at linaro.org> wrote:
> > +static int clk_gate2b_enable(struct clk *clk)
> > +{
> > +       struct clk_gate2b *gate2b = to_clk_gate2b(clk);
> > +       unsigned long flags;
> > +       u32 reg;
> > +
> > +       if (gate2b->lock)
> > +               spin_lock_irqsave(gate2b->lock, flags);
> 
> Are their bits in this register used by other clocks which aren't
> protected by the enable_lock spinlock?
For now, no. If I remove the lock, it'll limit the gate2b usage.
> 
> > +int clk_gate2b_set_val(struct clk *clk, int en, int dis)
> > +{
> > +       struct clk_gate2b *gate2b = to_clk_gate2b(clk);
> > +       unsigned long flags;
> > +       u32 reg, val;
> > +
> > +       en &= 0x3;
> > +       dis &= 0x3;
> > +
> > +       if (gate2b->lock)
> > +               spin_lock_irqsave(gate2b->lock, flags);
> > +
> > +       reg = __raw_readl(gate2b->reg);
> > +       val = (reg >> gate2b->shift) & 0x3;
> > +       reg &= ~(0x3 << gate2b->shift);
> > +       if (val == gate2b->val_en && val != en)
> > +               reg |= en << gate2b->shift;
> > +       else if (val == gate2b->val_dis && val != dis)
> > +               reg |= dis << gate2b->shift;
> > +       __raw_writel(reg, gate2b->reg);
> > +       gate2b->val_en = en;
> > +       gate2b->val_dis = dis;
> > +
> > +       if (gate2b->lock)
> > +               spin_unlock_irqrestore(gate2b->lock, flags);
> > +
> > +       return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(clk_gate2b_set_val);
> 
> Who calls clk_gate2b_set_val, and why?
It's an interface for busfreq. When I enable a gate2b, I may want it to be
active when cpu is running but disabled when wfi. I may also want it to be
active all the time, if some dma device also need it.
So the value I set for enable/disable change at runtime.

Thanks
Richard
> 
> Regards,
> Mike