drivers/soc/qcom/qcom_gsbi.c

   1 /*
   2  * Copyright (c) 2014, The Linux foundation. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License rev 2 and
   6  * only rev 2 as published by the free Software foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or fITNESS fOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <linux/clk.h>
  15 #include <linux/err.h>
  16 #include <linux/io.h>
  17 #include <linux/module.h>
  18 #include <linux/of.h>
  19 #include <linux/of_platform.h>
  20 #include <linux/platform_device.h>
  21
  22 #define GSBI_CTRL_REG           0x0000
  23 #define GSBI_PROTOCOL_SHIFT     4
  24
  25 struct gsbi_info {
  26         struct clk *hclk;
  27         u32 mode;
  28         u32 crci;
  29 };
  30
  31 static int gsbi_probe(struct platform_device *pdev)
  32 {
  33         struct device_node *node = pdev->dev.of_node;
  34         struct resource *res;
  35         void __iomem *base;
  36         struct gsbi_info *gsbi;
  37
  38         gsbi = devm_kzalloc(&pdev->dev, sizeof(*gsbi), GFP_KERNEL);
  39
  40         if (!gsbi)
  41                 return -ENOMEM;
  42
  43         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  44         base = devm_ioremap_resource(&pdev->dev, res);
  45         if (IS_ERR(base))
  46                 return PTR_ERR(base);
  47
  48         if (of_property_read_u32(node, "qcom,mode", &gsbi->mode)) {
  49                 dev_err(&pdev->dev, "missing mode configuration\n");
  50                 return -EINVAL;
  51         }
  52
  53         /* not required, so default to 0 if not present */
  54         of_property_read_u32(node, "qcom,crci", &gsbi->crci);
  55
  56         dev_info(&pdev->dev, "GSBI port protocol: %d crci: %d\n",
  57                  gsbi->mode, gsbi->crci);
  58         gsbi->hclk = devm_clk_get(&pdev->dev, "iface");
  59         if (IS_ERR(gsbi->hclk))
  60                 return PTR_ERR(gsbi->hclk);
  61
  62         clk_prepare_enable(gsbi->hclk);
  63
  64         writel_relaxed((gsbi->mode << GSBI_PROTOCOL_SHIFT) | gsbi->crci,
  65                                 base + GSBI_CTRL_REG);
  66
  67         /* make sure the gsbi control write is not reordered */
  68         wmb();
  69
  70         platform_set_drvdata(pdev, gsbi);
  71
  72         return of_platform_populate(node, NULL, NULL, &pdev->dev);
  73 }
  74
  75 static int gsbi_remove(struct platform_device *pdev)
  76 {
  77         struct gsbi_info *gsbi = platform_get_drvdata(pdev);
  78
  79         clk_disable_unprepare(gsbi->hclk);
  80
  81         return 0;
  82 }
  83
  84 static const struct of_device_id gsbi_dt_match[] = {
  85         { .compatible = "qcom,gsbi-v1.0.0", },
  86         { },
  87 };
  88
  89 MODULE_DEVICE_TABLE(of, gsbi_dt_match);
  90
  91 static struct platform_driver gsbi_driver = {
  92         .driver = {
  93                 .name           = "gsbi",
  94                 .of_match_table = gsbi_dt_match,
  95         },
  96         .probe = gsbi_probe,
  97         .remove = gsbi_remove,
  98 };
  99
 100 module_platform_driver(gsbi_driver);
 101
 102 MODULE_AUTHOR("Andy Gross <agross@codeaurora.org>");
 103 MODULE_DESCRIPTION("QCOM GSBI driver");
 104 MODULE_LICENSE("GPL v2");