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Linux/drivers/mmc/host/sdhci-cns3xxx.c

  1 /*
  2  * SDHCI support for CNS3xxx SoC
  3  *
  4  * Copyright 2008 Cavium Networks
  5  * Copyright 2010 MontaVista Software, LLC.
  6  *
  7  * Authors: Scott Shu
  8  *          Anton Vorontsov <avorontsov@mvista.com>
  9  *
 10  * This program is free software; you can redistribute it and/or modify
 11  * it under the terms of the GNU General Public License version 2 as
 12  * published by the Free Software Foundation.
 13  */
 14 
 15 #include <linux/delay.h>
 16 #include <linux/device.h>
 17 #include <linux/mmc/host.h>
 18 #include <linux/module.h>
 19 #include "sdhci-pltfm.h"
 20 
 21 static unsigned int sdhci_cns3xxx_get_max_clk(struct sdhci_host *host)
 22 {
 23         return 150000000;
 24 }
 25 
 26 static void sdhci_cns3xxx_set_clock(struct sdhci_host *host, unsigned int clock)
 27 {
 28         struct device *dev = mmc_dev(host->mmc);
 29         int div = 1;
 30         u16 clk;
 31         unsigned long timeout;
 32 
 33         if (clock == host->clock)
 34                 return;
 35 
 36         sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
 37 
 38         if (clock == 0)
 39                 goto out;
 40 
 41         while (host->max_clk / div > clock) {
 42                 /*
 43                  * On CNS3xxx divider grows linearly up to 4, and then
 44                  * exponentially up to 256.
 45                  */
 46                 if (div < 4)
 47                         div += 1;
 48                 else if (div < 256)
 49                         div *= 2;
 50                 else
 51                         break;
 52         }
 53 
 54         dev_dbg(dev, "desired SD clock: %d, actual: %d\n",
 55                 clock, host->max_clk / div);
 56 
 57         /* Divide by 3 is special. */
 58         if (div != 3)
 59                 div >>= 1;
 60 
 61         clk = div << SDHCI_DIVIDER_SHIFT;
 62         clk |= SDHCI_CLOCK_INT_EN;
 63         sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
 64 
 65         timeout = 20;
 66         while (!((clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL))
 67                         & SDHCI_CLOCK_INT_STABLE)) {
 68                 if (timeout == 0) {
 69                         dev_warn(dev, "clock is unstable");
 70                         break;
 71                 }
 72                 timeout--;
 73                 mdelay(1);
 74         }
 75 
 76         clk |= SDHCI_CLOCK_CARD_EN;
 77         sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
 78 out:
 79         host->clock = clock;
 80 }
 81 
 82 static const struct sdhci_ops sdhci_cns3xxx_ops = {
 83         .get_max_clock  = sdhci_cns3xxx_get_max_clk,
 84         .set_clock      = sdhci_cns3xxx_set_clock,
 85 };
 86 
 87 static const struct sdhci_pltfm_data sdhci_cns3xxx_pdata = {
 88         .ops = &sdhci_cns3xxx_ops,
 89         .quirks = SDHCI_QUIRK_BROKEN_DMA |
 90                   SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK |
 91                   SDHCI_QUIRK_INVERTED_WRITE_PROTECT |
 92                   SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN |
 93                   SDHCI_QUIRK_BROKEN_TIMEOUT_VAL |
 94                   SDHCI_QUIRK_NONSTANDARD_CLOCK,
 95 };
 96 
 97 static int sdhci_cns3xxx_probe(struct platform_device *pdev)
 98 {
 99         return sdhci_pltfm_register(pdev, &sdhci_cns3xxx_pdata, 0);
100 }
101 
102 static int sdhci_cns3xxx_remove(struct platform_device *pdev)
103 {
104         return sdhci_pltfm_unregister(pdev);
105 }
106 
107 static struct platform_driver sdhci_cns3xxx_driver = {
108         .driver         = {
109                 .name   = "sdhci-cns3xxx",
110                 .owner  = THIS_MODULE,
111                 .pm     = SDHCI_PLTFM_PMOPS,
112         },
113         .probe          = sdhci_cns3xxx_probe,
114         .remove         = sdhci_cns3xxx_remove,
115 };
116 
117 module_platform_driver(sdhci_cns3xxx_driver);
118 
119 MODULE_DESCRIPTION("SDHCI driver for CNS3xxx");
120 MODULE_AUTHOR("Scott Shu, "
121               "Anton Vorontsov <avorontsov@mvista.com>");
122 MODULE_LICENSE("GPL v2");
123 

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