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

From: [email-masked] (Stephen Boyd)
Date: Wed, 24 Aug 2016 01:34:15 -0700

On 08/19, Nishanth Menon wrote:
>  THANKO'S RAREMONO AM/FM/SW RADIO RECEIVER USB DRIVER
>  M:	Hans Verkuil <[email-masked]>
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index e2d9bd760c84..d1724999be78 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -179,6 +179,19 @@ config COMMON_CLK_NXP
>  	---help---
>  	  Support for clock providers on NXP platforms.
>  
> +if COMMON_CLK_KEYSTONE

Why not depends on COMMON_CLK_KEYSTONE? Or make the tristate have
an if COMMON_CLK_KEYSTONE after it? So far an if <CONFIG> hasn't
happened in this file. And is anything inside
drivers/clk/keystone used by this driver? Maybe this if statement
can just be dropped entirely and then the keystone/Makefile
updated?

> +
> +config TI_SCI_CLK
> +	tristate "TI System Control Interface clock drivers"
> +	depends on TI_SCI_PROTOCOL || COMPILE_TEST
> +	default y

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.
> +
> +endif # COMMON_CLK_KEYSTONE
> +
>  config COMMON_CLK_PALMAS
>  	tristate "Clock driver for TI Palmas devices"
>  	depends on MFD_PALMAS
> diff --git a/drivers/clk/keystone/sci-clk.c b/drivers/clk/keystone/sci-clk.c
> new file mode 100644
> index 000000000000..6c43e097e6d6
> --- /dev/null
> +++ b/drivers/clk/keystone/sci-clk.c
> @@ -0,0 +1,539 @@
> +/*
> + * SCI Clock driver for keystone based devices
> + *
> + * Copyright (C) 2015-2016 Texas Instruments Incorporated - http://www.ti.com/
> + *	Tero Kristo <[email-masked]>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> + * kind, whether express or implied; without even the implied warranty
> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +#include <linux/clk.h>

Is this include used?

> +#include <linux/clk-provider.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/soc/ti/ti_sci_protocol.h>
> +
> +#define SCI_CLK_SSC_ENABLE		BIT(0)
> +#define SCI_CLK_ALLOW_FREQ_CHANGE	BIT(1)
> +#define SCI_CLK_INPUT_TERMINATION	BIT(2)
> +
> +/**
> + * struct sci_clk_provider - TI SCI clock provider representation
> + * @sci:    Handle to the System Control Interface protocol handler
> + * @ops:    Pointer to the SCI ops to be used by the clocks
> + * @dev:    Device pointer for the clock provider
> + * @clocks: List of all registered clocks
> + * @lock:   Mutex for locking access to the @clocks list
> + */
> +struct sci_clk_provider {
> +	const struct ti_sci_handle *sci;
> +	const struct ti_sci_clk_ops *ops;
> +	struct device *dev;
> +	struct list_head clocks;
> +	struct mutex lock; /* Protects access to the @clocks list */
> +};
> +
> +/**
> + * struct sci_clk - TI SCI clock representation
> + * @hw:		 Hardware clock cookie for common clock framework
> + * @dev_id:	 Device index
> + * @clk_id:	 Clock index
> + * @node:	 Clocks list link
> + * @provider:	 Master clock provider
> + * @flags:	 Flags for the clock
> + */
> +struct sci_clk {
> +	struct clk_hw hw;
> +	u16 dev_id;
> +	u8 clk_id;
> +	struct list_head node;
> +	struct sci_clk_provider *provider;
> +	u8 flags;
> +};
> +
> +#define to_sci_clk(_hw) container_of(_hw, struct sci_clk, hw)
> +
> +/**
> + * sci_clk_prepare - Prepare (enable) a TI SCI clock
> + * @hw: clock to prepare
> + *
> + * Prepares a clock to be actively used. Returns the SCI protocol status.
> + */
> +static int sci_clk_prepare(struct clk_hw *hw)
> +{
> +	struct sci_clk *clk = to_sci_clk(hw);
> +	bool enable_ssc = clk->flags & SCI_CLK_SSC_ENABLE;
> +	bool allow_freq_change = clk->flags & SCI_CLK_ALLOW_FREQ_CHANGE;
> +	bool input_termination = clk->flags & SCI_CLK_INPUT_TERMINATION;
> +
> +	return clk->provider->ops->get_clock(clk->provider->sci, clk->dev_id,
> +					     clk->clk_id, enable_ssc,
> +					     allow_freq_change,
> +					     input_termination);
> +}
> +
> +/**
> + * sci_clk_unprepare - Un-prepares (disables) a TI SCI clock
> + * @hw: clock to unprepare
> + *
> + * Un-prepares a clock from active state.
> + */
> +static void sci_clk_unprepare(struct clk_hw *hw)
> +{
> +	struct sci_clk *clk = to_sci_clk(hw);
> +	int ret;
> +
> +	ret = clk->provider->ops->put_clock(clk->provider->sci, clk->dev_id,
> +					    clk->clk_id);
> +	if (ret)
> +		dev_err(clk->provider->dev,
> +			"unprepare failed for dev=%d, clk=%d, ret=%d\n",
> +			clk->dev_id, clk->clk_id, ret);
> +}
> +
> +/**
> + * sci_clk_is_prepared - Check if a TI SCI clock is prepared or not
> + * @hw: clock to check status for
> + *
> + * Checks if a clock is prepared (enabled) in hardware. Returns non-zero
> + * value if clock is enabled, zero otherwise.
> + */
> +static int sci_clk_is_prepared(struct clk_hw *hw)
> +{
> +	struct sci_clk *clk = to_sci_clk(hw);
> +	bool req_state, current_state;
> +	int ret;
> +
> +	ret = clk->provider->ops->is_on(clk->provider->sci, clk->dev_id,
> +					clk->clk_id, &req_state,
> +					&current_state);
> +	if (ret) {
> +		dev_err(clk->provider->dev,
> +			"prepare failed for dev=%d, clk=%d, ret=%d\n",

s/prepare/is_prepared/ ?

> +			clk->dev_id, clk->clk_id, ret);
> +		return 0;
> +	}
> +
> +	return req_state;
> +}
> +
> +/**
> + * 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;
> +}
> +
> +/**
> + * sci_clk_determine_rate - Determines a clock rate a clock can be set to
> + * @hw: clock to change rate for
> + * @req: requested rate configuration for the clock
> + *
> + * Determines a suitable clock rate and parent for a TI SCI clock.
> + * The parent handling is un-used, as generally the parent clock rates
> + * are not known by the kernel; instead these are internally handled
> + * by the firmware. Returns the new clock rate that can be set for the
> + * clock, or 0 in failure.
> + */
> +static int sci_clk_determine_rate(struct clk_hw *hw,
> +				  struct clk_rate_request *req)
> +{
> +	struct sci_clk *clk = to_sci_clk(hw);
> +	u64 new_rate;
> +	int ret;
> +
> +	ret = clk->provider->ops->get_best_match_freq(clk->provider->sci,
> +						      clk->dev_id,
> +						      clk->clk_id,
> +						      req->min_rate,
> +						      req->rate,
> +						      req->max_rate,
> +						      &new_rate);
> +	if (ret) {
> +		dev_err(clk->provider->dev,
> +			"determine-rate failed for dev=%d, clk=%d, ret=%d\n",
> +			clk->dev_id, clk->clk_id, ret);
> +		return 0;
> +	}
> +
> +	return (int)new_rate;

determine rate should return a negative number on failure and 0
on success. The actual rate that was found should go into
req->rate. This looks broken.

> +}
> +
> +/**
> + * sci_clk_set_rate - Set rate for a TI SCI clock
> + * @hw: clock to change rate for
> + * @rate: target rate for the clock
> + * @parent_rate: rate of the clock parent, not used for TI SCI clocks
> + *
> + * Sets a clock frequency for a TI SCI clock. Returns the TI SCI
> + * protocol status.
> + */
> +static int sci_clk_set_rate(struct clk_hw *hw, unsigned long rate,
> +			    unsigned long parent_rate)
> +{
> +	struct sci_clk *clk = to_sci_clk(hw);
> +	u64 freq = rate;

We can't just pass rate three times?

> +
> +	return clk->provider->ops->set_freq(clk->provider->sci, clk->dev_id,
> +					    clk->clk_id, freq, freq, freq);
> +}
> +
> +/**
> + * sci_clk_get_parent - Get the current parent of a TI SCI clock
> + * @hw: clock to get parent for
> + *
> + * Returns the index of the currently selected parent for a TI SCI clock.
> + */
> +static u8 sci_clk_get_parent(struct clk_hw *hw)
> +{
> +	struct sci_clk *clk = to_sci_clk(hw);
> +	u8 parent_id;
> +	int ret;
> +
> +	ret = clk->provider->ops->get_parent(clk->provider->sci, clk->dev_id,
> +					     clk->clk_id, &parent_id);
> +	if (ret) {
> +		dev_err(clk->provider->dev,
> +			"get-parent failed for dev=%d, clk=%d, ret=%d\n",
> +			clk->dev_id, clk->clk_id, ret);
> +		return 0;
> +	}
> +
> +	parent_id = parent_id - clk->clk_id - 1;
> +
> +	return parent_id;

Why not just return parent_id - clk->clk_id - 1?

> +}
> +
> +/**
> + * sci_clk_set_parent - Set the parent of a TI SCI clock
> + * @hw: clock to set parent for
> + * @index: new parent index for the clock
> + *
> + * Sets the parent of a TI SCI clock. Return TI SCI protocol status.
> + */
> +static int sci_clk_set_parent(struct clk_hw *hw, u8 index)
> +{
> +	struct sci_clk *clk = to_sci_clk(hw);
> +
> +	return clk->provider->ops->set_parent(clk->provider->sci, clk->dev_id,
> +					      clk->clk_id,
> +					      index + 1 + clk->clk_id);
> +}
> +
> +static const struct clk_ops sci_clk_ops = {
> +	.prepare = sci_clk_prepare,
> +	.unprepare = sci_clk_unprepare,
> +	.is_prepared = sci_clk_is_prepared,
> +	.recalc_rate = sci_clk_recalc_rate,
> +	.determine_rate = sci_clk_determine_rate,
> +	.set_rate = sci_clk_set_rate,
> +	.get_parent = sci_clk_get_parent,
> +	.set_parent = sci_clk_set_parent,
> +};
> +
> +/**
> + * _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
> + * @parse_parents: indicator whether parents for this clock should be handled
> + *
> + * Gets a handle to an existing TI SCI 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 clock struct, or ERR_PTR value in failure.
> + */

Please move this driver to clk_hw_register() and friends. This on
the fly clk generation is scary considering how we hold locks
while the provider is asked to give us the pointer, so allocating
and registering clks (basically reentering the CCF again) could
lead to a locking nightmare. Best to avoid that.

> +static struct clk *_sci_clk_get(struct sci_clk_provider *provider,
> +				u16 dev_id, u8 clk_id, bool parse_parents)
> +{
> +	struct clk_init_data init = { NULL };
> +	struct clk *clk;
> +	struct sci_clk *sci_clk = NULL;
> +	char name[20];
> +	char **parent_names = NULL;
> +	int i;
> +	int ret;
> +
> +	list_for_each_entry(sci_clk, &provider->clocks, node)
> +		if (sci_clk->dev_id == dev_id && sci_clk->clk_id == clk_id)
> +			return sci_clk->hw.clk;
> +
> +	sci_clk = devm_kzalloc(provider->dev, sizeof(*sci_clk), GFP_KERNEL);
> +	if (!sci_clk) {
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	sci_clk->dev_id = dev_id;
> +	sci_clk->clk_id = clk_id;
> +	sci_clk->provider = provider;
> +
> +	if (parse_parents) {
> +		ret = provider->ops->get_num_parents(provider->sci, dev_id,
> +						     clk_id,
> +						     &init.num_parents);
> +		if (ret)
> +			goto err;
> +	}
> +
> +	snprintf(name, 20, "%s:%d:%d", dev_name(provider->dev), sci_clk->dev_id,
> +		 sci_clk->clk_id);

I hope we don't make dev_name() longer than 20 characters

> +
> +	init.name = name;
> +
> +	if (init.num_parents < 2)
> +		init.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 = devm_kzalloc(provider->dev, 20,
> +						   GFP_KERNEL);
> +			if (!parent_name) {
> +				ret = -ENOMEM;
> +				goto err;
> +			}
> +			snprintf(parent_name, 20, "%s:%d:%d",
> +				 dev_name(provider->dev), sci_clk->dev_id,
> +				 sci_clk->clk_id + 1 + i);
> +			parent_names[i] = parent_name;
> +
> +			_sci_clk_get(provider, dev_id, clk_id + 1 + i, false);
> +		}
> +		init.parent_names = (const char * const *)parent_names;
> +	}
> +
> +	init.ops = &sci_clk_ops;
> +	sci_clk->hw.init = &init;
> +
> +	clk = devm_clk_register(provider->dev, &sci_clk->hw);
> +
> +	if (IS_ERR(clk)) {
> +		ret = PTR_ERR(clk);
> +		dev_err(provider->dev, "failed clk register with %d\n", ret);
> +		goto err;
> +	} else {
> +		list_add(&sci_clk->node, &provider->clocks);
> +	}
> +
> +	return clk;
> +
> +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);
> +	}
> +
> +	devm_kfree(provider->dev, sci_clk);
> +
> +	return ERR_PTR(ret);
> +}
> +
> +/**
> + * sci_clk_get - Xlate function for getting clock handles
> + * @clkspec: device tree clock specifier
> + * @data: pointer to the clock provider
> + *
> + * Xlate function for retrieving clock TI SCI clock handles based on
> + * device tree clock specifier. Called from the common clock framework,
> + * when a corresponding of_clk_get call is executed. Returns a pointer
> + * to the TI SCI clock struct, or ERR_PTR value in failure.
> + */
> +static struct clk *sci_clk_get(struct of_phandle_args *clkspec, void *data)
> +{
> +	struct sci_clk_provider *provider = data;
> +	struct clk *clk;
> +	u16 dev_id;
> +	u8 clk_id;
> +
> +	if (clkspec->args_count != 2)
> +		return ERR_PTR(-EINVAL);
> +
> +	mutex_lock(&provider->lock);
> +
> +	dev_id = clkspec->args[0];
> +	clk_id = clkspec->args[1];
> +
> +	clk = _sci_clk_get(provider, dev_id, clk_id, true);
> +
> +	mutex_unlock(&provider->lock);
> +
> +	return clk;
> +}
> +
> +static const struct of_device_id ti_sci_clk_of_match[] = {
> +	{ .compatible = "ti,sci-clk" },
> +	{ /* Sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, ti_sci_clk_of_match);
> +
> +/**
> + * ti_sci_clk_parse_flags - Helper function to parse clock flag arrays
> + * @dev: clock provider device
> + * @np: device node pointer for the clock provider
> + * @list_name: property name containing the clocks list
> + * @flag: flag to apply to the list of clocks
> + *
> + * Parses a DT list based on the provided data, and applies the flag value
> + * for each of the clocks identified by the list. Return 0 for success,
> + * negative error value for failure.
> + */
> +static int ti_sci_clk_parse_flags(struct device *dev, struct device_node *np,
> +				  const char *list_name, u8 flag)
> +{
> +	int num_clks;
> +	int i;
> +
> +	num_clks = of_count_phandle_with_args(np, list_name, "#clock-cells");
> +
> +	for (i = 0; i < num_clks; i++) {
> +		struct of_phandle_args clkspec;
> +		struct clk_hw *hw;
> +		struct sci_clk *sci_clk;
> +		struct clk *clk;
> +		int ret;
> +
> +		ret = of_parse_phandle_with_args(np, list_name, "#clock-cells",
> +						 i, &clkspec);

Do we really need to parse the phandle and get a clk from the
provider that is our own driver? We should be able to get a hw
pointer by calling our xlate_hw function with the two cells
instead and completely bypass generating a clk structure.

> +		if (ret) {
> +			dev_err(dev, "Failed to parse %s[%d] = %d\n", list_name,
> +				i, ret);
> +			return ret;
> +		}
> +		clk = of_clk_get_from_provider(&clkspec);
> +		if (IS_ERR(clk)) {
> +			dev_err(dev, "clk_get failed for %s[%d] = %ld\n",
> +				list_name, i, PTR_ERR(clk));
> +			return PTR_ERR(clk);
> +		}
> +		hw = __clk_get_hw(clk);
> +		sci_clk = to_sci_clk(hw);
> +
> +		sci_clk->flags |= flag;
> +	}
> +
> +	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;
> +
> +	if (!np) {
> +		dev_err(dev, "OF data missing\n");
> +		return -EINVAL;
> +	}

Is this ever true? Seems useless.

> +
> +	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;
> +
> +	INIT_LIST_HEAD(&provider->clocks);
> +	mutex_init(&provider->lock);
> +
> +	provider->sci = handle;
> +	provider->ops = &handle->ops.clk_ops;
> +	provider->dev = dev;
> +
> +	of_clk_add_provider(np, sci_clk_get, provider);

This could fail.

> +
> +	ti_sci_clk_parse_flags(dev, np, "ti,ssc-clocks", SCI_CLK_SSC_ENABLE);
> +	ti_sci_clk_parse_flags(dev, np, "ti,allow-freq-change-clocks",
> +			       SCI_CLK_ALLOW_FREQ_CHANGE);
> +	ti_sci_clk_parse_flags(dev, np, "ti,input-term-clocks",
> +			       SCI_CLK_INPUT_TERMINATION);
> +
> +	dev_info(dev, "initialized.\n");

debug noise?

> +
> +	return 0;
> +}
> +
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project