drivers/misc/vexpress_config.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2018 Arm Ltd
   4  * Author: Liviu Dudau <liviu.dudau@foss.arm.com>
   5  *
   6  */
   7 #include <common.h>
   8 #include <dm.h>
   9 #include <dm/read.h>
  10 #include <asm/io.h>
  11 #include <linux/delay.h>
  12 #include <misc.h>
  13
  14 #define SYS_CFGDATA             0xa0
  15
  16 #define SYS_CFGCTRL             0xa4
  17 #define SYS_CFGCTRL_START       BIT(31)
  18 #define SYS_CFGCTRL_WRITE       BIT(30)
  19
  20 #define SYS_CFGSTAT             0xa8
  21 #define SYS_CFGSTAT_ERR         BIT(1)
  22 #define SYS_CFGSTAT_COMPLETE    BIT(0)
  23
  24 struct vexpress_config_sysreg {
  25         phys_addr_t addr;
  26         u32 site;
  27 };
  28
  29 static int vexpress_config_exec(struct vexpress_config_sysreg *syscfg,
  30                                 bool write, void *buf, int size)
  31 {
  32         u32 cmd, status, tries = 100;
  33
  34         cmd = (*(u32 *)buf) | SYS_CFGCTRL_START | (syscfg->site << 16);
  35
  36         if (!write) {
  37                 /* write a canary in the data register for reads */
  38                 writel(0xdeadbeef, syscfg->addr + SYS_CFGDATA);
  39         } else {
  40                 cmd |= SYS_CFGCTRL_WRITE;
  41                 writel(((u32 *)buf)[1], syscfg->addr + SYS_CFGDATA);
  42         }
  43         writel(0, syscfg->addr + SYS_CFGSTAT);
  44         writel(cmd, syscfg->addr + SYS_CFGCTRL);
  45
  46         /* completion of command takes ages, go to sleep (150us) */
  47         do {
  48                 udelay(150);
  49                 status = readl(syscfg->addr + SYS_CFGSTAT);
  50                 if (status & SYS_CFGSTAT_ERR)
  51                         return -EFAULT;
  52         } while (--tries && !(status & SYS_CFGSTAT_COMPLETE));
  53
  54         if (!tries)
  55                 return -ETIMEDOUT;
  56
  57         if (!write)
  58                 (*(u32 *)buf) = readl(syscfg->addr + SYS_CFGDATA);
  59
  60         return 0;
  61 }
  62
  63 static int vexpress_config_read(struct udevice *dev,
  64                                 int offset, void *buf, int size)
  65 {
  66         struct vexpress_config_sysreg *priv = dev_get_uclass_priv(dev);
  67
  68         if (size != sizeof(u32))
  69                 return -EINVAL;
  70
  71         return vexpress_config_exec(priv, false, buf, size);
  72 }
  73
  74 static int vexpress_config_write(struct udevice *dev,
  75                                  int offset, const void *buf, int size)
  76 {
  77         struct vexpress_config_sysreg *priv = dev_get_uclass_priv(dev);
  78
  79         if (size != sizeof(u32) * 2)
  80                 return -EINVAL;
  81
  82         return vexpress_config_exec(priv, true, (void *)buf, size);
  83 }
  84
  85 static struct misc_ops vexpress_config_ops = {
  86         .read = vexpress_config_read,
  87         .write = vexpress_config_write,
  88 };
  89
  90 static int vexpress_config_probe(struct udevice *dev)
  91 {
  92         struct ofnode_phandle_args args;
  93         struct vexpress_config_sysreg *priv;
  94         const char *prop;
  95         int err, prop_size;
  96
  97         err = dev_read_phandle_with_args(dev, "arm,vexpress,config-bridge",
  98                                          NULL, 0, 0, &args);
  99         if (err)
 100                 return err;
 101
 102         prop = ofnode_get_property(args.node, "compatible", &prop_size);
 103         if (!prop || (strncmp(prop, "arm,vexpress-sysreg", 19) != 0))
 104                 return -ENOENT;
 105
 106         priv = calloc(1, sizeof(*priv));
 107         if (!priv)
 108                 return -ENOMEM;
 109
 110         dev->uclass_priv = priv;
 111         priv->addr = ofnode_get_addr(args.node);
 112
 113         return dev_read_u32(dev, "arm,vexpress,site", &priv->site);
 114 }
 115
 116 static const struct udevice_id vexpress_config_ids[] = {
 117         { .compatible = "arm,vexpress,config-bus" },
 118         { }
 119 };
 120
 121 U_BOOT_DRIVER(vexpress_config_drv) = {
 122         .name = "vexpress_config_bus",
 123         .id = UCLASS_MISC,
 124         .of_match = vexpress_config_ids,
 125         .bind = dm_scan_fdt_dev,
 126         .probe = vexpress_config_probe,
 127         .ops = &vexpress_config_ops,
 128 };