Subject: [PATCH 3/3] clk: keystone: Add sci-clk driver support

From: [email-masked] (Stephen Boyd)
Date: Wed, 7 Dec 2016 16:13:48 -0800

On 10/21, Tero Kristo wrote:
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index 6a8ac04..dce08a7 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -169,6 +169,15 @@ config COMMON_CLK_NXP
>  	---help---
>  	  Support for clock providers on NXP platforms.
>  
> +config TI_SCI_CLK
> +	tristate "TI System Control Interface clock drivers"
> +	depends on (TI_SCI_PROTOCOL && COMMON_CLK_KEYSTONE) || COMPILE_TEST

Given that we depend on COMMON_CLK_KEYSTONE (just for the
Makefile dependency?) this should be moved to right below the
COMMON_CLK_KEYSTONE config. And we should consider making a
Kconfig file in drivers/clk/keystone/ to hold both those configs
instead of having them at the toplevel.

> +	default TI_SCI_PROTOCOL
> +	---help---
> +	  This adds the clock driver support over TI System Control Interface.
> +	  If you wish to use clock resources from the PMMC firmware, say Y.
> +	  Otherwise, say N.
> +
>  config COMMON_CLK_PALMAS
>  	tristate "Clock driver for TI Palmas devices"
>  	depends on MFD_PALMAS
> diff --git a/drivers/clk/keystone/Makefile b/drivers/clk/keystone/Makefile
> index 0477cf6..0e7993d 100644
> --- a/drivers/clk/keystone/Makefile
> +++ b/drivers/clk/keystone/Makefile
> @@ -1 +1,2 @@
>  obj-y			+= pll.o gate.o
> +obj-$(CONFIG_TI_SCI_CLK)	+= sci-clk.o
> diff --git a/drivers/clk/keystone/sci-clk.c b/drivers/clk/keystone/sci-clk.c
> new file mode 100644
> index 0000000..f6af5bd
> --- /dev/null
> +++ b/drivers/clk/keystone/sci-clk.c
> @@ -0,0 +1,589 @@
[...]
> +
> +/**
> + * sci_clk_recalc_rate - Get clock rate for a TI SCI clock
> + * @hw: clock to get rate for
> + * @parent_rate: parent rate provided by common clock framework, not used
> + *
> + * Gets the current clock rate of a TI SCI clock. Returns the current
> + * clock rate, or zero in failure.
> + */
> +static unsigned long sci_clk_recalc_rate(struct clk_hw *hw,
> +					 unsigned long parent_rate)
> +{
> +	struct sci_clk *clk = to_sci_clk(hw);
> +	u64 freq;
> +	int ret;
> +
> +	ret = clk->provider->ops->get_freq(clk->provider->sci, clk->dev_id,
> +					   clk->clk_id, &freq);
> +	if (ret) {
> +		dev_err(clk->provider->dev,
> +			"recalc-rate failed for dev=%d, clk=%d, ret=%d\n",
> +			clk->dev_id, clk->clk_id, ret);
> +		return 0;
> +	}
> +
> +	return (u32)freq;

Do we need the cast? sizeof(u32) doesn't always equal
sizeof(unsigned long).

> +
> +/**
> + * _sci_clk_get - Gets a handle for an SCI clock
> + * @provider: Handle to SCI clock provider
> + * @dev_id: device ID for the clock to register
> + * @clk_id: clock ID for the clock to register
> + *
> + * Gets a handle to an existing TI SCI hw clock, or builds a new clock
> + * entry and registers it with the common clock framework. Called from
> + * the common clock framework, when a corresponding of_clk_get call is
> + * executed, or recursively from itself when parsing parent clocks.
> + * Returns a pointer to the hw clock struct, or ERR_PTR value in failure.
> + */
> +static struct clk_hw *_sci_clk_build(struct sci_clk_provider *provider,
> +				     u16 dev_id, u8 clk_id)
> +{
> +	struct clk_init_data init = { NULL };
> +	struct sci_clk *sci_clk = NULL;
> +	char *name = NULL;
> +	char **parent_names = NULL;
> +	int i;
> +	int ret;
> +
> +	sci_clk = devm_kzalloc(provider->dev, sizeof(*sci_clk), GFP_KERNEL);
> +	if (!sci_clk)
> +		return ERR_PTR(-ENOMEM);
> +
> +	sci_clk->dev_id = dev_id;
> +	sci_clk->clk_id = clk_id;
> +	sci_clk->provider = provider;
> +
> +	ret = provider->ops->get_num_parents(provider->sci, dev_id,
> +					     clk_id,
> +					     &init.num_parents);
> +	if (ret)
> +		goto err;
> +
> +	name = kasprintf(GFP_KERNEL, "%s:%d:%d", dev_name(provider->dev),
> +			 sci_clk->dev_id, sci_clk->clk_id);
> +
> +	init.name = name;
> +
> +	if (init.num_parents < 2)
> +		init.num_parents = 0;

This deserves a comment. Why is num_parents == 1 the same as
num_parents == 0?

> +
> +	if (init.num_parents) {
> +		parent_names = devm_kcalloc(provider->dev, init.num_parents,
> +					    sizeof(char *), GFP_KERNEL);
> +
> +		if (!parent_names) {
> +			ret = -ENOMEM;
> +			goto err;
> +		}
> +
> +		for (i = 0; i < init.num_parents; i++) {
> +			char *parent_name;
> +
> +			parent_name = kasprintf(GFP_KERNEL, "%s:%d:%d",
> +						dev_name(provider->dev),
> +						sci_clk->dev_id,
> +						sci_clk->clk_id + 1 + i);
> +			if (!parent_name) {
> +				ret = -ENOMEM;
> +				goto err;
> +			}
> +			parent_names[i] = parent_name;
> +		}
> +		init.parent_names = (const char * const *)parent_names;

Does that really need a cast?

> +	}
> +
> +	init.ops = &sci_clk_ops;
> +	sci_clk->hw.init = &init;
> +
> +	ret = devm_clk_hw_register(provider->dev, &sci_clk->hw);
> +	if (ret) {
> +		dev_err(provider->dev, "failed clk register with %d\n", ret);
> +		goto err;
> +	}
> +	kfree(name);
> +
> +	return &sci_clk->hw;
> +
> +err:
> +	if (parent_names) {
> +		for (i = 0; i < init.num_parents; i++)
> +			devm_kfree(provider->dev, parent_names[i]);
> +
> +		devm_kfree(provider->dev, parent_names);

Shouldn't we be freeing the parent names all the time? It should
be deep copied in the framework.

> +	}
> +
> +	devm_kfree(provider->dev, sci_clk);
> +
> +	kfree(name);
> +
> +	return ERR_PTR(ret);
> +}
[..]
> +
> +static int ti_sci_init_clocks(struct sci_clk_provider *p)
> +{
> +	struct sci_clk_data *data = p->clocks;
> +	struct clk_hw *hw;
> +	int i;
> +
> +	while (data->num_clks) {
> +		data->clocks = devm_kcalloc(p->dev, data->num_clks,
> +					    sizeof(struct sci_clk),
> +					    GFP_KERNEL);
> +		if (!data->clocks)
> +			return -ENOMEM;
> +
> +		for (i = 0; i < data->num_clks; i++) {
> +			hw = _sci_clk_build(p, data->dev, i);
> +			if (!IS_ERR(hw)) {
> +				data->clocks[i] = hw;
> +				continue;
> +			}
> +
> +			/* Skip any holes in the clock lists */
> +			if (PTR_ERR(hw) == -ENODEV)

Does this happen? I don't see where _sci_clk_build() returns
-ENODEV.

> +				continue;
> +
> +			return PTR_ERR(hw);
> +		}
> +		data++;
> +	}
> +
> +	return 0;
> +}
> +

> +
> +/**
> + * ti_sci_clk_probe - Probe function for the TI SCI clock driver
> + * @pdev: platform device pointer to be probed
> + *
> + * Probes the TI SCI clock device. Allocates a new clock provider
> + * and registers this to the common clock framework. Also applies
> + * any required flags to the identified clocks via clock lists
> + * supplied from DT. Returns 0 for success, negative error value
> + * for failure.
> + */
> +static int ti_sci_clk_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->of_node;
> +	struct sci_clk_provider *provider;
> +	const struct ti_sci_handle *handle;
> +	struct sci_clk_data *data;
> +	int ret;
> +
> +	data = (struct sci_clk_data *)
> +		of_match_node(ti_sci_clk_of_match, np)->data;

Just use of_device_get_match_data() instead.

> +
> +	handle = devm_ti_sci_get_handle(dev);
> +	if (IS_ERR(handle))
> +		return PTR_ERR(handle);
> +
> +	provider = devm_kzalloc(dev, sizeof(*provider), GFP_KERNEL);
> +	if (!provider)
> +		return -ENOMEM;
> +
> +	provider->clocks = data;
> +
> +	provider->sci = handle;
> +	provider->ops = &handle->ops.clk_ops;
> +	provider->dev = dev;
> +
> +	ti_sci_init_clocks(provider);

And if this fails?

> +
> +	ret = of_clk_add_hw_provider(np, sci_clk_get, provider);
> +	if (ret)
> +		return ret;
> +
> +	return 0;

Just "return of_clk_add_hw_provider()" please.

> +}

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