/*
   * 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>
  
  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 void ti_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 ti_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);
  }
  
  /**
   * of_ti_clk_allow_autoidle_all - enable autoidle for all clocks
   *
   * Enables hardware autoidle for all registered DT clocks, which have
   * the feature.
   */
  void of_ti_clk_allow_autoidle_all(void)
  {
  	struct clk_ti_autoidle *c;
  
  	list_for_each_entry(c, &autoidle_clks, node)
  		ti_allow_autoidle(c);
  }
  
  /**
   * of_ti_clk_deny_autoidle_all - disable autoidle for all clocks
   *
   * Disables hardware autoidle for all registered DT clocks, which have
   * the feature.
   */
  void of_ti_clk_deny_autoidle_all(void)
  {
  	struct clk_ti_autoidle *c;
  
  	list_for_each_entry(c, &autoidle_clks, node)
  		ti_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 (!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;
  }