On Mon, Dec 17, 2012 at 06:58:23PM +0100, Lucas Stach wrote:
[...]
> +static int tegra20_plld_clk_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long parent_rate)
> +{
> + struct clk_tegra *c = to_clk_tegra(hw);
> + unsigned long input_rate = parent_rate;
> + u64 n = 0;
> + int m_max, m_min, m = 0;
> + u32 val, rem = 0;
> + u8 cpcon = 0;
> +
> + m_max = input_rate / c->u.pll.cf_min;
> + m_min = (input_rate / c->u.pll.cf_max) + 1;
> +
> + for (m = m_min; m <= m_max; m++) {
> + n = (u64)rate * m;
> + rem = do_div(n, input_rate);
> + if (!rem)
> + break;
> + }
> +
> + if (rem)
> + return -EINVAL;
This code is common to both .round_rate() and .set_rate() so maybe you
should factor it out.
> +
> + c->mul = n;
> + c->div = n;
> +
> + val = clk_readl(c->reg + PLL_BASE);
> + val &= ~(PLL_BASE_DIVP_MASK | PLL_BASE_DIVN_MASK |
> + PLL_BASE_DIVM_MASK);
> + val |= (m << PLL_BASE_DIVM_SHIFT) | (n << PLL_BASE_DIVN_SHIFT);
> + clk_writel(val, c->reg + PLL_BASE);
> +
> + if (n <= 50)
> + cpcon = 2;
> + else if (n <= 300)
> + cpcon = 4;
> + else if (n <= 600)
> + cpcon = 8;
> + else if (n <= 1000)
> + cpcon = 12;
> +
> + val = clk_readl(c->reg + PLL_MISC(c));
> + val &= ~PLL_MISC_CPCON_MASK;
> + val |= cpcon << PLL_MISC_CPCON_SHIFT;
> + clk_writel(val, c->reg + PLL_MISC(c));
> +
> +
There's a gratuitous blank line here.
Other than that this algorithm looks pretty much like what I came up
with in an earlier prototype. One difference is that I used an
additional outer loop for the p-divider. Taking that into account should
allow even more frequencies to be matched.
Thierry
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