drivers/reset/starfive/reset-starfive-jh7100.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Reset driver for the StarFive JH7100 SoC
   4  *
   5  * Copyright (C) 2021 Emil Renner Berthing <kernel@esmil.dk>
   6  */
   7
   8 #include <linux/mod_devicetable.h>
   9 #include <linux/platform_device.h>
  10
  11 #include "reset-starfive-jh71x0.h"
  12
  13 #include <dt-bindings/reset/starfive-jh7100.h>
  14
  15 /* register offsets */
  16 #define JH7100_RESET_ASSERT0    0x00
  17 #define JH7100_RESET_ASSERT1    0x04
  18 #define JH7100_RESET_ASSERT2    0x08
  19 #define JH7100_RESET_ASSERT3    0x0c
  20 #define JH7100_RESET_STATUS0    0x10
  21 #define JH7100_RESET_STATUS1    0x14
  22 #define JH7100_RESET_STATUS2    0x18
  23 #define JH7100_RESET_STATUS3    0x1c
  24
  25 /*
  26  * Writing a 1 to the n'th bit of the m'th ASSERT register asserts
  27  * line 32m + n, and writing a 0 deasserts the same line.
  28  * Most reset lines have their status inverted so a 0 bit in the STATUS
  29  * register means the line is asserted and a 1 means it's deasserted. A few
  30  * lines don't though, so store the expected value of the status registers when
  31  * all lines are asserted.
  32  */
  33 static const u32 jh7100_reset_asserted[4] = {
  34         /* STATUS0 */
  35         BIT(JH7100_RST_U74 % 32) |
  36         BIT(JH7100_RST_VP6_DRESET % 32) |
  37         BIT(JH7100_RST_VP6_BRESET % 32),
  38         /* STATUS1 */
  39         BIT(JH7100_RST_HIFI4_DRESET % 32) |
  40         BIT(JH7100_RST_HIFI4_BRESET % 32),
  41         /* STATUS2 */
  42         BIT(JH7100_RST_E24 % 32),
  43         /* STATUS3 */
  44         0,
  45 };
  46
  47 static int __init jh7100_reset_probe(struct platform_device *pdev)
  48 {
  49         void __iomem *base = devm_platform_ioremap_resource(pdev, 0);
  50
  51         if (IS_ERR(base))
  52                 return PTR_ERR(base);
  53
  54         return reset_starfive_jh71x0_register(&pdev->dev, pdev->dev.of_node,
  55                                               base + JH7100_RESET_ASSERT0,
  56                                               base + JH7100_RESET_STATUS0,
  57                                               jh7100_reset_asserted,
  58                                               JH7100_RSTN_END,
  59                                               THIS_MODULE);
  60 }
  61
  62 static const struct of_device_id jh7100_reset_dt_ids[] = {
  63         { .compatible = "starfive,jh7100-reset" },
  64         { /* sentinel */ }
  65 };
  66
  67 static struct platform_driver jh7100_reset_driver = {
  68         .driver = {
  69                 .name = "jh7100-reset",
  70                 .of_match_table = jh7100_reset_dt_ids,
  71                 .suppress_bind_attrs = true,
  72         },
  73 };
  74 builtin_platform_driver_probe(jh7100_reset_driver, jh7100_reset_probe);