[PATCH v4 09/16] reset: starfive-jh7100: Add StarFive JH7100 reset driver

Emil Renner Berthing
2021-11-16T15:06:13Z

Add a driver for the StarFive JH7100 reset controller.

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
---
MAINTAINERS | 7 +
drivers/reset/Kconfig | 7 +
drivers/reset/Makefile | 1 +
drivers/reset/reset-starfive-jh7100.c | 176 ++++++++++++++++++++++++++
4 files changed, 191 insertions(+)
create mode 100644 drivers/reset/reset-starfive-jh7100.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 2548ef1f8246..1152f5d94690 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18137,6 +18137,13 @@ F: Documentation/devicetree/bindings/clock/starfive,jh7100-clkgen.yaml
F: drivers/clk/starfive/clk-starfive-jh7100.c
F: include/dt-bindings/clock/starfive-jh7100.h

+STARFIVE JH7100 RESET CONTROLLER DRIVER
+M: Emil Renner Berthing <kernel@esmil.dk>
+S: Maintained
+F: Documentation/devicetree/bindings/reset/starfive,jh7100-reset.yaml
+F: drivers/reset/reset-starfive-jh7100.c
+F: include/dt-bindings/reset/starfive-jh7100.h
+
STATIC BRANCH/CALL
M: Peter Zijlstra <peterz@infradead.org>
M: Josh Poimboeuf <jpoimboe@redhat.com>
diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 85024eb1d2ea..6f8ba0ddc05f 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -224,6 +224,13 @@ config RESET_SOCFPGA
This enables the reset driver for the SoCFPGA ARMv7 platforms. This
driver gets initialized early during platform init calls.

+config RESET_STARFIVE_JH7100
+ bool "StarFive JH7100 Reset Driver"
+ depends on SOC_STARFIVE || COMPILE_TEST
+ default SOC_STARFIVE
+ help
+ This enables the reset controller driver for the StarFive JH7100 SoC.
+
config RESET_SUNXI
bool "Allwinner SoCs Reset Driver" if COMPILE_TEST && !ARCH_SUNXI
default ARCH_SUNXI
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 21d46d8869ff..bd0a97be18b5 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_RESET_RZG2L_USBPHY_CTRL) += reset-rzg2l-usbphy-ctrl.o
obj-$(CONFIG_RESET_SCMI) += reset-scmi.o
obj-$(CONFIG_RESET_SIMPLE) += reset-simple.o
obj-$(CONFIG_RESET_SOCFPGA) += reset-socfpga.o
+obj-$(CONFIG_RESET_STARFIVE_JH7100) += reset-starfive-jh7100.o
obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o
obj-$(CONFIG_RESET_TI_SCI) += reset-ti-sci.o
obj-$(CONFIG_RESET_TI_SYSCON) += reset-ti-syscon.o
diff --git a/drivers/reset/reset-starfive-jh7100.c b/drivers/reset/reset-starfive-jh7100.c
new file mode 100644
index 000000000000..2f7615cbf1dc
--- /dev/null
+++ b/drivers/reset/reset-starfive-jh7100.c
@@ -0,0 +1,176 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Reset driver for the StarFive JH7100 SoC
+ *
+ * Copyright (C) 2021 Emil Renner Berthing <kernel@esmil.dk>
+ */
+
+#include <linux/bitmap.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/spinlock.h>
+
+#include <dt-bindings/reset/starfive-jh7100.h>
+
+/* register offsets */
+#define JH7100_RESET_ASSERT0 0x00
+#define JH7100_RESET_ASSERT1 0x04
+#define JH7100_RESET_ASSERT2 0x08
+#define JH7100_RESET_ASSERT3 0x0c
+#define JH7100_RESET_STATUS0 0x10
+#define JH7100_RESET_STATUS1 0x14
+#define JH7100_RESET_STATUS2 0x18
+#define JH7100_RESET_STATUS3 0x1c
+
+#if BITS_PER_LONG == 64
+#define jh7100_reset_read readq
+#define jh7100_reset_write writeq
+#else
+#define jh7100_reset_read readl
+#define jh7100_reset_write writel
+#endif
+
+/*
+ * Writing a 1 to the n'th bit of the m'th ASSERT register asserts
+ * line 32m + n, and writing a 0 deasserts the same line.
+ * Most reset lines have their status inverted so a 0 bit in the STATUS
+ * register means the line is asserted and a 1 means it's deasserted. A few
+ * lines don't though, so store the expected value of the status registers when
+ * all lines are asserted.
+ */
+static const DECLARE_BITMAP(jh7100_reset_asserted, 4 * 32) = {
+ BITMAP_FROM_U64(BIT_ULL_MASK(JH7100_RST_U74) |
+ BIT_ULL_MASK(JH7100_RST_VP6_DRESET) |
+ BIT_ULL_MASK(JH7100_RST_VP6_BRESET) |
+ BIT_ULL_MASK(JH7100_RST_HIFI4_DRESET) |
+ BIT_ULL_MASK(JH7100_RST_HIFI4_BRESET)),
+ BITMAP_FROM_U64(BIT_ULL_MASK(JH7100_RST_E24)),
+};
+
+struct jh7100_reset {
+ struct reset_controller_dev rcdev;
+ /* protect registers against concurrent read-modify-write */
+ spinlock_t lock;
+ void __iomem *base;
+};
+
+static inline struct jh7100_reset *
+jh7100_reset_from(struct reset_controller_dev *rcdev)
+{
+ return container_of(rcdev, struct jh7100_reset, rcdev);
+}
+
+static int jh7100_reset_update(struct reset_controller_dev *rcdev,
+ unsigned long id, bool assert)
+{
+ struct jh7100_reset *data = jh7100_reset_from(rcdev);
+ unsigned long offset = id / BITS_PER_LONG;
+ void __iomem *reg_assert = data->base + JH7100_RESET_ASSERT0 + offset * sizeof(long);
+ void __iomem *reg_status = data->base + JH7100_RESET_STATUS0 + offset * sizeof(long);
+ unsigned long mask = BIT_MASK(id);
+ unsigned long done = jh7100_reset_asserted[offset] & mask;
+ unsigned long value;
+ unsigned long flags;
+ int ret;
+
+ if (!assert)
+ done ^= mask;
+
+ spin_lock_irqsave(&data->lock, flags);
+
+ value = jh7100_reset_read(reg_assert);
+ if (assert)
+ value |= mask;
+ else
+ value &= ~mask;
+ jh7100_reset_write(value, reg_assert);
+
+ /* if the associated clock is gated, deasserting might otherwise hang forever */
+ ret = readx_poll_timeout_atomic(jh7100_reset_read, reg_status, value,
+ (value & mask) == done, 0, 1000);
+
+ spin_unlock_irqrestore(&data->lock, flags);
+ return ret;
+}
+
+static int jh7100_reset_assert(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ return jh7100_reset_update(rcdev, id, true);
+}
+
+static int jh7100_reset_deassert(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ return jh7100_reset_update(rcdev, id, false);
+}
+
+static int jh7100_reset_reset(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ int ret;
+
+ ret = jh7100_reset_assert(rcdev, id);
+ if (ret)
+ return ret;
+
+ return jh7100_reset_deassert(rcdev, id);
+}
+
+static int jh7100_reset_status(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct jh7100_reset *data = jh7100_reset_from(rcdev);
+ unsigned long offset = id / BITS_PER_LONG;
+ void __iomem *reg_status = data->base + JH7100_RESET_STATUS0 + offset * sizeof(long);
+ unsigned long value = jh7100_reset_read(reg_status);
+ unsigned long mask = BIT_MASK(id);
+
+ return !((value ^ jh7100_reset_asserted[offset]) & mask);
+}
+
+static const struct reset_control_ops jh7100_reset_ops = {
+ .assert = jh7100_reset_assert,
+ .deassert = jh7100_reset_deassert,
+ .reset = jh7100_reset_reset,
+ .status = jh7100_reset_status,
+};
+
+static int __init jh7100_reset_probe(struct platform_device *pdev)
+{
+ struct jh7100_reset *data;
+
+ data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(data->base))
+ return PTR_ERR(data->base);
+
+ data->rcdev.ops = &jh7100_reset_ops;
+ data->rcdev.owner = THIS_MODULE;
+ data->rcdev.nr_resets = JH7100_RSTN_END;
+ data->rcdev.dev = &pdev->dev;
+ data->rcdev.of_node = pdev->dev.of_node;
+ spin_lock_init(&data->lock);
+
+ return devm_reset_controller_register(&pdev->dev, &data->rcdev);
+}
+
+static const struct of_device_id jh7100_reset_dt_ids[] = {
+ { .compatible = "starfive,jh7100-reset" },
+ { /* sentinel */ }
+};
+
+static struct platform_driver jh7100_reset_driver = {
+ .driver = {
+ .name = "jh7100-reset",
+ .of_match_table = jh7100_reset_dt_ids,
+ .suppress_bind_attrs = true,
+ },
+};
+builtin_platform_driver_probe(jh7100_reset_driver, jh7100_reset_probe);
--
2.33.1