drivers/soc/litex: Add restart handler

Let the LiteX SoC Controller register a restart handler, which resets
the LiteX SoC by writing 1 to CSR_CTRL_RESET_ADDR.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Stafford Horne <shorne@gmail.com>

diff --git a/drivers/soc/litex/litex_soc_ctrl.c b/drivers/soc/litex/litex_soc_ctrl.c
index da17ba5..a7dd5be 100644 (file)
--- a/drivers/soc/litex/litex_soc_ctrl.c
+++ b/drivers/soc/litex/litex_soc_ctrl.c
@@ -15,6 +15,11 @@
 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/io.h>
+#include <linux/reboot.h>
+
+/* reset register located at the base address */
+#define RESET_REG_OFF           0x00
+#define RESET_REG_VALUE         0x00000001
 
 #define SCRATCH_REG_OFF         0x04
 #define SCRATCH_REG_VALUE       0x12345678
@@ -66,8 +71,19 @@ static int litex_check_csr_access(void __iomem *reg_addr)
 
 struct litex_soc_ctrl_device {
        void __iomem *base;
+       struct notifier_block reset_nb;
 };
 
+static int litex_reset_handler(struct notifier_block *this, unsigned long mode,
+                              void *cmd)
+{
+       struct litex_soc_ctrl_device *soc_ctrl_dev =
+               container_of(this, struct litex_soc_ctrl_device, reset_nb);
+
+       litex_write32(soc_ctrl_dev->base + RESET_REG_OFF, RESET_REG_VALUE);
+       return NOTIFY_DONE;
+}
+
 static const struct of_device_id litex_soc_ctrl_of_match[] = {
        {.compatible = "litex,soc-controller"},
        {},
@@ -78,6 +94,7 @@ MODULE_DEVICE_TABLE(of, litex_soc_ctrl_of_match);
 static int litex_soc_ctrl_probe(struct platform_device *pdev)
 {
        struct litex_soc_ctrl_device *soc_ctrl_dev;
+       int error;
 
        soc_ctrl_dev = devm_kzalloc(&pdev->dev, sizeof(*soc_ctrl_dev), GFP_KERNEL);
        if (!soc_ctrl_dev)
@@ -87,7 +104,29 @@ static int litex_soc_ctrl_probe(struct platform_device *pdev)
        if (IS_ERR(soc_ctrl_dev->base))
                return PTR_ERR(soc_ctrl_dev->base);
 
-       return litex_check_csr_access(soc_ctrl_dev->base);
+       error = litex_check_csr_access(soc_ctrl_dev->base);
+       if (error)
+               return error;
+
+       platform_set_drvdata(pdev, soc_ctrl_dev);
+
+       soc_ctrl_dev->reset_nb.notifier_call = litex_reset_handler;
+       soc_ctrl_dev->reset_nb.priority = 128;
+       error = register_restart_handler(&soc_ctrl_dev->reset_nb);
+       if (error) {
+               dev_warn(&pdev->dev, "cannot register restart handler: %d\n",
+                        error);
+       }
+
+       return 0;
+}
+
+static int litex_soc_ctrl_remove(struct platform_device *pdev)
+{
+       struct litex_soc_ctrl_device *soc_ctrl_dev = platform_get_drvdata(pdev);
+
+       unregister_restart_handler(&soc_ctrl_dev->reset_nb);
+       return 0;
 }
 
 static struct platform_driver litex_soc_ctrl_driver = {
@@ -96,6 +135,7 @@ static struct platform_driver litex_soc_ctrl_driver = {
                .of_match_table = of_match_ptr(litex_soc_ctrl_of_match)
        },
        .probe = litex_soc_ctrl_probe,
+       .remove = litex_soc_ctrl_remove,
 };
 
 module_platform_driver(litex_soc_ctrl_driver);