reset: Add a Gemini reset controller

The Cortina Systems Gemini reset controller is a simple
32bit register with self-deasserting reset lines. It is
accessed using regmap over syscon.

Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

3 files changed, 118 insertions, 0 deletions

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 42d5631c6da0..61fabf6ddaec 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -34,6 +34,13 @@ config RESET_BERLIN
         help
           This enables the reset controller driver for Marvell Berlin SoCs.
 
+config RESET_GEMINI
+        bool "Gemini Reset Driver" if COMPILE_TEST
+        default ARCH_GEMINI
+        select MFD_SYSCON
+        help
+          This enables the reset controller driver for Cortina Systems Gemini.
+
 config RESET_IMX7
         bool "i.MX7 Reset Driver" if COMPILE_TEST
         default SOC_IMX7D
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 26270e0f8342..e422a04f7b85 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -5,6 +5,7 @@ obj-$(CONFIG_ARCH_TEGRA) += tegra/
 obj-$(CONFIG_RESET_A10SR) += reset-a10sr.o
 obj-$(CONFIG_RESET_ATH79) += reset-ath79.o
 obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
+obj-$(CONFIG_RESET_GEMINI) += reset-gemini.o
 obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
 obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
 obj-$(CONFIG_RESET_MESON) += reset-meson.o
diff --git a/drivers/reset/reset-gemini.c b/drivers/reset/reset-gemini.c
new file mode 100644
index 000000000000..a2478997c75b
--- /dev/null
+++ b/drivers/reset/reset-gemini.c
@@ -0,0 +1,110 @@
+/*
+ * Cortina Gemini Reset controller driver
+ * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <dt-bindings/reset/cortina,gemini-reset.h>
+
+/**
+ * struct gemini_reset - gemini reset controller
+ * @map: regmap to access the containing system controller
+ * @rcdev: reset controller device
+ */
+struct gemini_reset {
+        struct regmap *map;
+        struct reset_controller_dev rcdev;
+};
+
+#define GEMINI_GLOBAL_SOFT_RESET 0x0c
+
+#define to_gemini_reset(p) \
+        container_of((p), struct gemini_reset, rcdev)
+
+/*
+ * This is a self-deasserting reset controller.
+ */
+static int gemini_reset(struct reset_controller_dev *rcdev,
+                        unsigned long id)
+{
+        struct gemini_reset *gr = to_gemini_reset(rcdev);
+
+        /* Manual says to always set BIT 30 (CPU1) to 1 */
+        return regmap_write(gr->map,
+                            GEMINI_GLOBAL_SOFT_RESET,
+                            BIT(GEMINI_RESET_CPU1) | BIT(id));
+}
+
+static int gemini_reset_status(struct reset_controller_dev *rcdev,
+                             unsigned long id)
+{
+        struct gemini_reset *gr = to_gemini_reset(rcdev);
+        u32 val;
+        int ret;
+
+        ret = regmap_read(gr->map, GEMINI_GLOBAL_SOFT_RESET, &val);
+        if (ret)
+                return ret;
+
+        return !!(val & BIT(id));
+}
+
+static const struct reset_control_ops gemini_reset_ops = {
+        .reset = gemini_reset,
+        .status = gemini_reset_status,
+};
+
+static int gemini_reset_probe(struct platform_device *pdev)
+{
+        struct gemini_reset *gr;
+        struct device *dev = &pdev->dev;
+        struct device_node *np = dev->of_node;
+        int ret;
+
+        gr = devm_kzalloc(dev, sizeof(*gr), GFP_KERNEL);
+        if (!gr)
+                return -ENOMEM;
+
+        gr->map = syscon_node_to_regmap(np);
+        if (IS_ERR(gr->map)) {
+                ret = PTR_ERR(gr->map);
+                dev_err(dev, "unable to get regmap (%d)", ret);
+                return ret;
+        }
+        gr->rcdev.owner = THIS_MODULE;
+        gr->rcdev.nr_resets = 32;
+        gr->rcdev.ops = &gemini_reset_ops;
+        gr->rcdev.of_node = pdev->dev.of_node;
+
+        ret = devm_reset_controller_register(&pdev->dev, &gr->rcdev);
+        if (ret)
+                return ret;
+
+        dev_info(dev, "registered Gemini reset controller\n");
+        return 0;
+}
+
+static const struct of_device_id gemini_reset_dt_ids[] = {
+        { .compatible = "cortina,gemini-syscon", },
+        { /* sentinel */ },
+};
+
+static struct platform_driver gemini_reset_driver = {
+        .probe  = gemini_reset_probe,
+        .driver = {
+                .name           = "gemini-reset",
+                .of_match_table = gemini_reset_dt_ids,
+                .suppress_bind_attrs = true,
+        },
+};
+builtin_platform_driver(gemini_reset_driver);