[RFC/PATCH 03/10] [ARM] tegra: Add clock support

[Russell King - ARM Linux]

On Mon, Mar 15, 2010 at 11:41:21PM -0700, konkers at google.com wrote:
> From: Colin Cross <ccross at android.com>
> 
> Signed-off-by: Colin Cross <ccross at android.com>
> Signed-off-by: Erik Gilling <konkers at android.com>
> ---
>  arch/arm/Kconfig                          |    1 +
>  arch/arm/mach-tegra/Makefile              |    2 +
>  arch/arm/mach-tegra/clock.c               |  191 +++++++
>  arch/arm/mach-tegra/clock.h               |  103 ++++
>  arch/arm/mach-tegra/common.c              |    1 +
>  arch/arm/mach-tegra/include/mach/clkdev.h |   32 ++
>  arch/arm/mach-tegra/tegra2_clocks.c       |  837 +++++++++++++++++++++++++++++
>  7 files changed, 1167 insertions(+), 0 deletions(-)
>  create mode 100644 arch/arm/mach-tegra/clock.c
>  create mode 100644 arch/arm/mach-tegra/clock.h
>  create mode 100644 arch/arm/mach-tegra/include/mach/clkdev.h
>  create mode 100644 arch/arm/mach-tegra/tegra2_clocks.c
> 
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 1232104..a5be2d6 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -576,6 +576,7 @@ config ARCH_TEGRA
>          select GENERIC_CLOCKEVENTS
>          select GENERIC_GPIO
>          select HAVE_CLK
> +        select COMMON_CLKDEV

These should be indented using tabs, not spaces.

> +/**
> + * clk_preinit - initialize any fields in the struct clk before clk init
> + * @clk: struct clk * to initialize
> + *
> + * Initialize any struct clk fields needed before normal clk initialization
> + * can run.  No return value.
> + */
> +void clk_preinit(struct clk *c)
> +{
> +	c->lock = __SPIN_LOCK_UNLOCKED(c->lock);

	spin_lock_init(&c->lock);

> +int clk_set_parent(struct clk *c, struct clk *parent)
> +{
> +	unsigned long flags;
> +	int ret = 0;
> +	spin_lock_irqsave(&c->lock, flags);
> +	if (c->ops && c->ops->set_parent)
> +		ret = c->ops->set_parent(c, parent);
> +	else
> +		BUG();

Does this condition really justify crashing the kernel?  Why not just
return an error?

> +int clk_set_rate(struct clk *c, unsigned long rate)
> +{
> +	int ret = 0;
> +	unsigned long flags;
> +	spin_lock_irqsave(&c->lock, flags);
> +	if (c->ops && c->ops->set_rate)
> +		ret = c->ops->set_rate(c, rate);
> +	else
> +		BUG();

Ditto.

> +unsigned long clk_get_rate(struct clk *c)
> +{
> +	int ret = 0;
> +	unsigned long flags;
> +	spin_lock_irqsave(&c->lock, flags);
> +	if (c->ops && c->ops->get_rate)
> +		ret = c->ops->get_rate(c);
> +	else if (c->parent)
> +		ret = clk_get_rate(c->parent);
> +	else
> +		BUG();

Ditto.

> +/* PLL Functions */
> +static int tegra2_pll_clk_set_rate(struct clk *c, unsigned long rate)
> +{
> +	u32 val;
> +	unsigned long input_rate;
> +	const struct clk_pll_table *sel;
> +
> +	pr_debug("%s on clock %s\n", __func__, c->name);
> +	/* BUG_ON(c->refcnt != 0); */
> +
> +	input_rate = clk_get_rate(c->parent);
> +	for (sel = c->pll_table; sel->input_rate != 0; sel++) {
> +		if (sel->input_rate == input_rate && sel->output_rate == rate) {
> +			c->n = sel->n;
> +			c->m = sel->m;
> +			c->p = sel->p;
> +			c->cpcon = sel->cpcon;
> +			val = clk_readl(c->reg + PLL_BASE);
> +			if (c->flags & PLL_FIXED)
> +				val |= PLL_BASE_OVERRIDE;
> +			val &= ~(PLL_BASE_DIVP_MASK | PLL_BASE_DIVN_MASK |
> +				 PLL_BASE_DIVM_MASK);
> +			val |= (c->m << PLL_BASE_DIVM_SHIFT) |
> +				(c->n << PLL_BASE_DIVN_SHIFT);
> +			BUG_ON(c->p > 2);
> +			if (c->p == 2)
> +				val |= 1 << PLL_BASE_DIVP_SHIFT;
> +			clk_writel(val, c->reg + PLL_BASE);
> +			c->rate = rate;
> +
> +			if (c->flags & PLL_HAS_CPCON) {
> +				val = c->cpcon << PLL_MISC_CPCON_SHIFT;
> +				clk_writel(val, c->reg + PLL_MISC);
> +			}
> +			return 0;
> +		}
> +	}
> +	return 1;

What's this 'return 1' on error and 'return 0' on  success?  The clk API
uses standard Linux error codes, which are negative constants on error.
Please use a standard constant from the errno.h headers.