/*
   * TI clock autoidle support
   *
   * Copyright (C) 2013 Texas Instruments, Inc.
   *
   * Tero Kristo <t-kristo@ti.com>
   *
   * 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-provider.h>
  #include <linux/slab.h>
  #include <linux/io.h>
  #include <linux/of.h>
  #include <linux/of_address.h>
  #include <linux/clk/ti.h>
  
  #include "clock.h"
  
  struct clk_ti_autoidle {
  	void __iomem		*reg;
  	u8			shift;
  	u8			flags;
  	const char		*name;
  	struct list_head	node;
  };
  
  #define AUTOIDLE_LOW		0x1
  
  static LIST_HEAD(autoidle_clks);
  static LIST_HEAD(clk_hw_omap_clocks);
  
  /**
   * omap2_clk_deny_idle - disable autoidle on an OMAP clock
   * @clk: struct clk * to disable autoidle for
   *
   * Disable autoidle on an OMAP clock.
   */
  int omap2_clk_deny_idle(struct clk *clk)
  {
  	struct clk_hw_omap *c;
  
  	c = to_clk_hw_omap(__clk_get_hw(clk));
  	if (c->ops && c->ops->deny_idle)
  		c->ops->deny_idle(c);
  	return 0;
  }
  
  /**
   * omap2_clk_allow_idle - enable autoidle on an OMAP clock
   * @clk: struct clk * to enable autoidle for
   *
   * Enable autoidle on an OMAP clock.
   */
  int omap2_clk_allow_idle(struct clk *clk)
  {
  	struct clk_hw_omap *c;
  
  	c = to_clk_hw_omap(__clk_get_hw(clk));
  	if (c->ops && c->ops->allow_idle)
  		c->ops->allow_idle(c);
  	return 0;
  }
  
  static void _allow_autoidle(struct clk_ti_autoidle *clk)
  {
  	u32 val;
  
  	val = ti_clk_ll_ops->clk_readl(clk->reg);
  
  	if (clk->flags & AUTOIDLE_LOW)
  		val &= ~(1 << clk->shift);
  	else
  		val |= (1 << clk->shift);
  
  	ti_clk_ll_ops->clk_writel(val, clk->reg);
  }
  
  static void _deny_autoidle(struct clk_ti_autoidle *clk)
  {
  	u32 val;
  
  	val = ti_clk_ll_ops->clk_readl(clk->reg);
  
  	if (clk->flags & AUTOIDLE_LOW)
  		val |= (1 << clk->shift);
  	else
  		val &= ~(1 << clk->shift);
  
  	ti_clk_ll_ops->clk_writel(val, clk->reg);
  }
  
  /**
   * _clk_generic_allow_autoidle_all - enable autoidle for all clocks
   *
   * Enables hardware autoidle for all registered DT clocks, which have
   * the feature.
   */
  static void _clk_generic_allow_autoidle_all(void)
  {
  	struct clk_ti_autoidle *c;
  
  	list_for_each_entry(c, &autoidle_clks, node)
  		_allow_autoidle(c);
  }
  
  /**
   * _clk_generic_deny_autoidle_all - disable autoidle for all clocks
   *
   * Disables hardware autoidle for all registered DT clocks, which have
   * the feature.
   */
  static void _clk_generic_deny_autoidle_all(void)
  {
  	struct clk_ti_autoidle *c;
  
  	list_for_each_entry(c, &autoidle_clks, node)
  		_deny_autoidle(c);
  }
  
  /**
   * of_ti_clk_autoidle_setup - sets up hardware autoidle for a clock
   * @node: pointer to the clock device node
   *
   * Checks if a clock has hardware autoidle support or not (check
   * for presence of 'ti,autoidle-shift' property in the device tree
   * node) and sets up the hardware autoidle feature for the clock
   * if available. If autoidle is available, the clock is also added
   * to the autoidle list for later processing. Returns 0 on success,
   * negative error value on failure.
   */
  int __init of_ti_clk_autoidle_setup(struct device_node *node)
  {
  	u32 shift;
  	struct clk_ti_autoidle *clk;
  
  	/* Check if this clock has autoidle support or not */
  	if (of_property_read_u32(node, "ti,autoidle-shift", &shift))
  		return 0;
  
  	clk = kzalloc(sizeof(*clk), GFP_KERNEL);
  
  	if (!clk)
  		return -ENOMEM;
  
  	clk->shift = shift;
  	clk->name = node->name;
  	clk->reg = ti_clk_get_reg_addr(node, 0);
  
  	if (IS_ERR(clk->reg)) {
  		kfree(clk);
  		return -EINVAL;
  	}
  
  	if (of_property_read_bool(node, "ti,invert-autoidle-bit"))
  		clk->flags |= AUTOIDLE_LOW;
  
  	list_add(&clk->node, &autoidle_clks);
  
  	return 0;
  }
  
  /**
   * omap2_init_clk_hw_omap_clocks - initialize an OMAP clock
   * @hw: struct clk_hw * to initialize
   *
   * Add an OMAP clock @clk to the internal list of OMAP clocks.  Used
   * temporarily for autoidle handling, until this support can be
   * integrated into the common clock framework code in some way.  No
   * return value.
   */
  void omap2_init_clk_hw_omap_clocks(struct clk_hw *hw)
  {
  	struct clk_hw_omap *c;
  
  	if (clk_hw_get_flags(hw) & CLK_IS_BASIC)
  		return;
  
  	c = to_clk_hw_omap(hw);
  	list_add(&c->node, &clk_hw_omap_clocks);
  }
  
  /**
   * omap2_clk_enable_autoidle_all - enable autoidle on all OMAP clocks that
   * support it
   *
   * Enable clock autoidle on all OMAP clocks that have allow_idle
   * function pointers associated with them.  This function is intended
   * to be temporary until support for this is added to the common clock
   * code.  Returns 0.
   */
  int omap2_clk_enable_autoidle_all(void)
  {
  	struct clk_hw_omap *c;
  
  	list_for_each_entry(c, &clk_hw_omap_clocks, node)
  		if (c->ops && c->ops->allow_idle)
  			c->ops->allow_idle(c);
  
  	_clk_generic_allow_autoidle_all();
  
  	return 0;
  }
  
  /**
   * omap2_clk_disable_autoidle_all - disable autoidle on all OMAP clocks that
   * support it
   *
   * Disable clock autoidle on all OMAP clocks that have allow_idle
   * function pointers associated with them.  This function is intended
   * to be temporary until support for this is added to the common clock
   * code.  Returns 0.
   */
  int omap2_clk_disable_autoidle_all(void)
  {
  	struct clk_hw_omap *c;
  
  	list_for_each_entry(c, &clk_hw_omap_clocks, node)
  		if (c->ops && c->ops->deny_idle)
  			c->ops->deny_idle(c);
  
  	_clk_generic_deny_autoidle_all();
  
  	return 0;
  }