drivers/clk/clk-twl6040.c

   1 /*
   2 * TWL6040 clock module driver for OMAP4 McPDM functional clock
   3 *
   4 * Copyright (C) 2012 Texas Instruments Inc.
   5 * Peter Ujfalusi <peter.ujfalusi@ti.com>
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License
   9 * version 2 as published by the Free Software Foundation.
  10 *
  11 * This program is distributed in the hope that it will be useful, but
  12 * WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14 * General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with this program; if not, write to the Free Software
  18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  19 * 02110-1301 USA
  20 *
  21 */
  22
  23 #include <linux/module.h>
  24 #include <linux/slab.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/mfd/twl6040.h>
  27 #include <linux/clk-provider.h>
  28
  29 struct twl6040_pdmclk {
  30         struct twl6040 *twl6040;
  31         struct device *dev;
  32         struct clk_hw pdmclk_hw;
  33         int enabled;
  34 };
  35
  36 static int twl6040_pdmclk_is_prepared(struct clk_hw *hw)
  37 {
  38         struct twl6040_pdmclk *pdmclk = container_of(hw, struct twl6040_pdmclk,
  39                                                      pdmclk_hw);
  40
  41         return pdmclk->enabled;
  42 }
  43
  44 static int twl6040_pdmclk_reset_one_clock(struct twl6040_pdmclk *pdmclk,
  45                                           unsigned int reg)
  46 {
  47         const u8 reset_mask = TWL6040_HPLLRST;  /* Same for HPPLL and LPPLL */
  48         int ret;
  49
  50         ret = twl6040_set_bits(pdmclk->twl6040, reg, reset_mask);
  51         if (ret < 0)
  52                 return ret;
  53
  54         ret = twl6040_clear_bits(pdmclk->twl6040, reg, reset_mask);
  55         if (ret < 0)
  56                 return ret;
  57
  58         return 0;
  59 }
  60
  61 /*
  62  * TWL6040A2 Phoenix Audio IC erratum #6: "PDM Clock Generation Issue At
  63  * Cold Temperature". This affects cold boot and deeper idle states it
  64  * seems. The workaround consists of resetting HPPLL and LPPLL.
  65  */
  66 static int twl6040_pdmclk_quirk_reset_clocks(struct twl6040_pdmclk *pdmclk)
  67 {
  68         int ret;
  69
  70         ret = twl6040_pdmclk_reset_one_clock(pdmclk, TWL6040_REG_HPPLLCTL);
  71         if (ret)
  72                 return ret;
  73
  74         ret = twl6040_pdmclk_reset_one_clock(pdmclk, TWL6040_REG_LPPLLCTL);
  75         if (ret)
  76                 return ret;
  77
  78         return 0;
  79 }
  80
  81 static int twl6040_pdmclk_prepare(struct clk_hw *hw)
  82 {
  83         struct twl6040_pdmclk *pdmclk = container_of(hw, struct twl6040_pdmclk,
  84                                                      pdmclk_hw);
  85         int ret;
  86
  87         ret = twl6040_power(pdmclk->twl6040, 1);
  88         if (ret)
  89                 return ret;
  90
  91         ret = twl6040_pdmclk_quirk_reset_clocks(pdmclk);
  92         if (ret)
  93                 goto out_err;
  94
  95         pdmclk->enabled = 1;
  96
  97         return 0;
  98
  99 out_err:
 100         dev_err(pdmclk->dev, "%s: error %i\n", __func__, ret);
 101         twl6040_power(pdmclk->twl6040, 0);
 102
 103         return ret;
 104 }
 105
 106 static void twl6040_pdmclk_unprepare(struct clk_hw *hw)
 107 {
 108         struct twl6040_pdmclk *pdmclk = container_of(hw, struct twl6040_pdmclk,
 109                                                      pdmclk_hw);
 110         int ret;
 111
 112         ret = twl6040_power(pdmclk->twl6040, 0);
 113         if (!ret)
 114                 pdmclk->enabled = 0;
 115
 116 }
 117
 118 static unsigned long twl6040_pdmclk_recalc_rate(struct clk_hw *hw,
 119                                                 unsigned long parent_rate)
 120 {
 121         struct twl6040_pdmclk *pdmclk = container_of(hw, struct twl6040_pdmclk,
 122                                                      pdmclk_hw);
 123
 124         return twl6040_get_sysclk(pdmclk->twl6040);
 125 }
 126
 127 static const struct clk_ops twl6040_pdmclk_ops = {
 128         .is_prepared = twl6040_pdmclk_is_prepared,
 129         .prepare = twl6040_pdmclk_prepare,
 130         .unprepare = twl6040_pdmclk_unprepare,
 131         .recalc_rate = twl6040_pdmclk_recalc_rate,
 132 };
 133
 134 static struct clk_init_data twl6040_pdmclk_init = {
 135         .name = "pdmclk",
 136         .ops = &twl6040_pdmclk_ops,
 137         .flags = CLK_GET_RATE_NOCACHE,
 138 };
 139
 140 static int twl6040_pdmclk_probe(struct platform_device *pdev)
 141 {
 142         struct twl6040 *twl6040 = dev_get_drvdata(pdev->dev.parent);
 143         struct twl6040_pdmclk *clkdata;
 144         int ret;
 145
 146         clkdata = devm_kzalloc(&pdev->dev, sizeof(*clkdata), GFP_KERNEL);
 147         if (!clkdata)
 148                 return -ENOMEM;
 149
 150         clkdata->dev = &pdev->dev;
 151         clkdata->twl6040 = twl6040;
 152
 153         clkdata->pdmclk_hw.init = &twl6040_pdmclk_init;
 154         ret = devm_clk_hw_register(&pdev->dev, &clkdata->pdmclk_hw);
 155         if (ret)
 156                 return ret;
 157
 158         platform_set_drvdata(pdev, clkdata);
 159
 160         return of_clk_add_hw_provider(pdev->dev.parent->of_node,
 161                                       of_clk_hw_simple_get,
 162                                       &clkdata->pdmclk_hw);
 163 }
 164
 165 static struct platform_driver twl6040_pdmclk_driver = {
 166         .driver = {
 167                 .name = "twl6040-pdmclk",
 168         },
 169         .probe = twl6040_pdmclk_probe,
 170 };
 171
 172 module_platform_driver(twl6040_pdmclk_driver);
 173
 174 MODULE_DESCRIPTION("TWL6040 clock driver for McPDM functional clock");
 175 MODULE_AUTHOR("Peter Ujfalusi <peter.ujfalusi@ti.com>");
 176 MODULE_ALIAS("platform:twl6040-pdmclk");
 177 MODULE_LICENSE("GPL");