Re: [PATCH 1/5] clk: berlin: add common pll driver

From: Stephen Boyd
Date: Thu Oct 01 2015 - 18:32:27 EST


On 09/22, Jisheng Zhang wrote:
> diff --git a/drivers/clk/berlin/pll.c b/drivers/clk/berlin/pll.c
> new file mode 100644
> index 0000000..9aad0b6
> --- /dev/null
> +++ b/drivers/clk/berlin/pll.c
> @@ -0,0 +1,119 @@
> +
> +#define to_berlin_pll(hw) container_of(hw, struct berlin_pll, hw)
> +
> +static u8 vcodiv_berlin[] = {1, 2, 4, 8, 16, 32, 64, 128};

This is an array of 1 << index position...

> +
> +static unsigned long berlin_pll_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + u32 val, fbdiv, rfdiv, vcodivsel, bypass;
> + struct berlin_pll *pll = to_berlin_pll(hw);
> +
> + bypass = readl_relaxed(pll->bypass);
> + if (bypass & (1 << pll->bypass_shift))
> + return parent_rate;
> +
> + val = readl_relaxed(pll->ctrl + PLL_CTRL0);
> + fbdiv = (val >> 12) & 0x1FF;
> + rfdiv = (val >> 3) & 0x1FF;
> + val = readl_relaxed(pll->ctrl + PLL_CTRL1);
> + vcodivsel = (val >> 9) & 0x7;
> + return parent_rate * fbdiv * 4 / rfdiv /
> + vcodiv_berlin[vcodivsel];

so we can replace this with 1 << vcodivsel?

> +}
> +
> +static u8 berlin_pll_get_parent(struct clk_hw *hw)
> +{
> + struct berlin_pll *pll = to_berlin_pll(hw);
> + u32 bypass = readl_relaxed(pll->bypass);
> +
> + if (bypass & (1 << pll->bypass_shift))
> + return 1;
> + else
> + return 0;

Simplify this to

if (bypass & (1 << pll->bypass_shift))
return 1;
return 0;

or

return !!(bypass & (1 << pll->bypass_shift))

> +}
> +
> +static const struct clk_ops berlin_pll_ops = {
> + .recalc_rate = berlin_pll_recalc_rate,
> + .get_parent = berlin_pll_get_parent,
> +};
> +
> +void __init berlin_pll_setup(struct device_node *np)

static?

> +{
> + struct clk_init_data init;
> + struct berlin_pll *pll;
> + const char *parent_names[PLL_SOURCE_MAX];
> + struct clk *clk;
> + int ret, num_parents;
> +
> + num_parents = of_clk_get_parent_count(np);
> + if (num_parents <= 0 || num_parents > PLL_SOURCE_MAX)
> + return;
> +
> + of_clk_parent_fill(np, parent_names, num_parents);
> +
> + pll = kzalloc(sizeof(*pll), GFP_KERNEL);
> + if (WARN_ON(!pll))

We already print a big warning on allocation failures, so drop
the WARN_ON please.

> + return;
> +
> + pll->ctrl = of_iomap(np, 0);
> + pll->bypass = of_iomap(np, 1);
> + ret = of_property_read_u8(np, "bypass-shift", &pll->bypass_shift);
> + if (WARN_ON(!pll->ctrl || !pll->bypass || ret))
> + return;
> +
> + init.name = np->name;
> + init.ops = &berlin_pll_ops;
> + init.parent_names = parent_names;
> + init.num_parents = num_parents;

init.flags is not initialized. Please initialize the init struct
on the stack to 0 to avoid future problems.

> +
> + pll->hw.init = &init;
> +
> + clk = clk_register(NULL, &pll->hw);
> + if (WARN_ON(IS_ERR(clk)))
> + return;
> +
> + ret = of_clk_add_provider(np, of_clk_src_simple_get, clk);
> + if (WARN_ON(ret))
> + return;

This return is useless.

> +}

--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/