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 <malloc.h>
  10 #include <dm/read.h>
  11 #include <asm/io.h>
  12 #include <linux/delay.h>
  13 #include <misc.h>
  14
  15 #define SYS_CFGDATA             0xa0
  16
  17 #define SYS_CFGCTRL             0xa4
  18 #define SYS_CFGCTRL_START       BIT(31)
  19 #define SYS_CFGCTRL_WRITE       BIT(30)
  20
  21 #define SYS_CFGSTAT             0xa8
  22 #define SYS_CFGSTAT_ERR         BIT(1)
  23 #define SYS_CFGSTAT_COMPLETE    BIT(0)
  24
  25 struct vexpress_config_sysreg {
  26         phys_addr_t addr;
  27         u32 site;
  28 };
  29
  30 static int vexpress_config_exec(struct vexpress_config_sysreg *syscfg,
  31                                 bool write, void *buf, int size)
  32 {
  33         u32 cmd, status, tries = 100;
  34
  35         cmd = (*(u32 *)buf) | SYS_CFGCTRL_START | (syscfg->site << 16);
  36
  37         if (!write) {
  38                 /* write a canary in the data register for reads */
  39                 writel(0xdeadbeef, syscfg->addr + SYS_CFGDATA);
  40         } else {
  41                 cmd |= SYS_CFGCTRL_WRITE;
  42                 writel(((u32 *)buf)[1], syscfg->addr + SYS_CFGDATA);
  43         }
  44         writel(0, syscfg->addr + SYS_CFGSTAT);
  45         writel(cmd, syscfg->addr + SYS_CFGCTRL);
  46
  47         /* completion of command takes ages, go to sleep (150us) */
  48         do {
  49                 udelay(150);
  50                 status = readl(syscfg->addr + SYS_CFGSTAT);
  51                 if (status & SYS_CFGSTAT_ERR)
  52                         return -EFAULT;
  53         } while (--tries && !(status & SYS_CFGSTAT_COMPLETE));
  54
  55         if (!tries)
  56                 return -ETIMEDOUT;
  57
  58         if (!write)
  59                 (*(u32 *)buf) = readl(syscfg->addr + SYS_CFGDATA);
  60
  61         return 0;
  62 }
  63
  64 static int vexpress_config_read(struct udevice *dev,
  65                                 int offset, void *buf, int size)
  66 {
  67         struct vexpress_config_sysreg *priv = dev_get_uclass_priv(dev);
  68
  69         if (size != sizeof(u32))
  70                 return -EINVAL;
  71
  72         return vexpress_config_exec(priv, false, buf, size);
  73 }
  74
  75 static int vexpress_config_write(struct udevice *dev,
  76                                  int offset, const void *buf, int size)
  77 {
  78         struct vexpress_config_sysreg *priv = dev_get_uclass_priv(dev);
  79
  80         if (size != sizeof(u32) * 2)
  81                 return -EINVAL;
  82
  83         return vexpress_config_exec(priv, true, (void *)buf, size);
  84 }
  85
  86 static struct misc_ops vexpress_config_ops = {
  87         .read = vexpress_config_read,
  88         .write = vexpress_config_write,
  89 };
  90
  91 static int vexpress_config_probe(struct udevice *dev)
  92 {
  93         struct ofnode_phandle_args args;
  94         struct vexpress_config_sysreg *priv;
  95         const char *prop;
  96         int err, prop_size;
  97
  98         err = dev_read_phandle_with_args(dev, "arm,vexpress,config-bridge",
  99                                          NULL, 0, 0, &args);
 100         if (err)
 101                 return err;
 102
 103         prop = ofnode_get_property(args.node, "compatible", &prop_size);
 104         if (!prop || (strncmp(prop, "arm,vexpress-sysreg", 19) != 0))
 105                 return -ENOENT;
 106
 107         priv = calloc(1, sizeof(*priv));
 108         if (!priv)
 109                 return -ENOMEM;
 110
 111         dev->uclass_priv = priv;
 112         priv->addr = ofnode_get_addr(args.node);
 113
 114         return dev_read_u32(dev, "arm,vexpress,site", &priv->site);
 115 }
 116
 117 static const struct udevice_id vexpress_config_ids[] = {
 118         { .compatible = "arm,vexpress,config-bus" },
 119         { }
 120 };
 121
 122 U_BOOT_DRIVER(vexpress_config_drv) = {
 123         .name = "vexpress_config_bus",
 124         .id = UCLASS_MISC,
 125         .of_match = vexpress_config_ids,
 126         .bind = dm_scan_fdt_dev,
 127         .probe = vexpress_config_probe,
 128         .ops = &vexpress_config_ops,
 129 };