[PATCH v2 03/12] reset: add polarfire soc reset support

Conor Dooley
2022-07-04T12:16:36Z

Add support for the resets on Microchip's PolarFire SoC (MPFS).
Reset control is a single register, wedged in between registers for
clock control. To fit with existed DT etc, the reset controller is
created using the aux device framework & set up in the clock driver.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
drivers/reset/Kconfig | 7 ++
drivers/reset/Makefile | 2 +-
drivers/reset/reset-mpfs.c | 157 +++++++++++++++++++++++++++++++++++++
3 files changed, 165 insertions(+), 1 deletion(-)
create mode 100644 drivers/reset/reset-mpfs.c

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 93c8d07ee328..edfdc7b2bc5f 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -122,6 +122,13 @@ config RESET_MCHP_SPARX5
help
This driver supports switch core reset for the Microchip Sparx5 SoC.

+config RESET_POLARFIRE_SOC
+ bool "Microchip PolarFire SoC (MPFS) Reset Driver"
+ depends on AUXILIARY_BUS && MCHP_CLK_MPFS
+ default MCHP_CLK_MPFS
+ help
+ This driver supports peripheral reset for the Microchip PolarFire SoC
+
config RESET_MESON
tristate "Meson Reset Driver"
depends on ARCH_MESON || COMPILE_TEST
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index a80a9c4008a7..5fac3a753858 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_RESET_K210) += reset-k210.o
obj-$(CONFIG_RESET_LANTIQ) += reset-lantiq.o
obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
obj-$(CONFIG_RESET_MCHP_SPARX5) += reset-microchip-sparx5.o
+obj-$(CONFIG_RESET_POLARFIRE_SOC) += reset-mpfs.o
obj-$(CONFIG_RESET_MESON) += reset-meson.o
obj-$(CONFIG_RESET_MESON_AUDIO_ARB) += reset-meson-audio-arb.o
obj-$(CONFIG_RESET_NPCM) += reset-npcm.o
@@ -38,4 +39,3 @@ obj-$(CONFIG_RESET_UNIPHIER) += reset-uniphier.o
obj-$(CONFIG_RESET_UNIPHIER_GLUE) += reset-uniphier-glue.o
obj-$(CONFIG_RESET_ZYNQ) += reset-zynq.o
obj-$(CONFIG_ARCH_ZYNQMP) += reset-zynqmp.o
-
diff --git a/drivers/reset/reset-mpfs.c b/drivers/reset/reset-mpfs.c
new file mode 100644
index 000000000000..1580d1b68d61
--- /dev/null
+++ b/drivers/reset/reset-mpfs.c
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * PolarFire SoC (MPFS) Peripheral Clock Reset Controller
+ *
+ * Author: Conor Dooley <conor.dooley@microchip.com>
+ * Copyright (c) 2022 Microchip Technology Inc. and its subsidiaries.
+ *
+ */
+#include <linux/auxiliary_bus.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <dt-bindings/clock/microchip,mpfs-clock.h>
+#include <soc/microchip/mpfs.h>
+
+/*
+ * The ENVM reset is the lowest bit in the register & I am using the CLK_FOO
+ * defines in the dt to make things easier to configure - so this is accounting
+ * for the offset of 3 there.
+ */
+#define MPFS_PERIPH_OFFSET CLK_ENVM
+#define MPFS_NUM_RESETS 30u
+#define MPFS_SLEEP_MIN_US 100
+#define MPFS_SLEEP_MAX_US 200
+
+/* block concurrent access to the soft reset register */
+static DEFINE_SPINLOCK(mpfs_reset_lock);
+
+/*
+ * Peripheral clock resets
+ */
+
+static int mpfs_assert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+ unsigned long flags;
+ u32 reg;
+
+ spin_lock_irqsave(&mpfs_reset_lock, flags);
+
+ reg = mpfs_reset_read(rcdev->dev);
+ reg |= BIT(id);
+ mpfs_reset_write(rcdev->dev, reg);
+
+ spin_unlock_irqrestore(&mpfs_reset_lock, flags);
+
+ return 0;
+}
+
+static int mpfs_deassert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+ unsigned long flags;
+ u32 reg, val;
+
+ spin_lock_irqsave(&mpfs_reset_lock, flags);
+
+ reg = mpfs_reset_read(rcdev->dev);
+ val = reg & ~BIT(id);
+ mpfs_reset_write(rcdev->dev, val);
+
+ spin_unlock_irqrestore(&mpfs_reset_lock, flags);
+
+ return 0;
+}
+
+static int mpfs_status(struct reset_controller_dev *rcdev, unsigned long id)
+{
+ u32 reg = mpfs_reset_read(rcdev->dev);
+
+ /*
+ * It is safe to return here as MPFS_NUM_RESETS makes sure the sign bit
+ * is never hit.
+ */
+ return (reg & BIT(id));
+}
+
+static int mpfs_reset(struct reset_controller_dev *rcdev, unsigned long id)
+{
+ mpfs_assert(rcdev, id);
+
+ usleep_range(MPFS_SLEEP_MIN_US, MPFS_SLEEP_MAX_US);
+
+ mpfs_deassert(rcdev, id);
+
+ return 0;
+}
+
+static const struct reset_control_ops mpfs_reset_ops = {
+ .reset = mpfs_reset,
+ .assert = mpfs_assert,
+ .deassert = mpfs_deassert,
+ .status = mpfs_status,
+};
+
+static int mpfs_reset_xlate(struct reset_controller_dev *rcdev,
+ const struct of_phandle_args *reset_spec)
+{
+ unsigned int index = reset_spec->args[0];
+
+ /*
+ * CLK_RESERVED does not map to a clock, but it does map to a reset,
+ * so it has to be accounted for here. It is the reset for the fabric,
+ * so if this reset gets called - do not reset it.
+ */
+ if (index == CLK_RESERVED) {
+ dev_err(rcdev->dev, "Resetting the fabric is not supported\n");
+ return -EINVAL;
+ }
+
+ if (index < MPFS_PERIPH_OFFSET || index >= (MPFS_PERIPH_OFFSET + rcdev->nr_resets)) {
+ dev_err(rcdev->dev, "Invalid reset index %u\n", index);
+ return -EINVAL;
+ }
+
+ return index - MPFS_PERIPH_OFFSET;
+}
+
+static int mpfs_reset_probe(struct auxiliary_device *adev,
+ const struct auxiliary_device_id *id)
+{
+ struct device *dev = &adev->dev;
+ struct reset_controller_dev *rcdev;
+
+ rcdev = devm_kzalloc(dev, sizeof(*rcdev), GFP_KERNEL);
+ if (!rcdev)
+ return -ENOMEM;
+
+ rcdev->dev = dev;
+ rcdev->dev->parent = dev->parent;
+ rcdev->ops = &mpfs_reset_ops;
+ rcdev->of_node = dev->parent->of_node;
+ rcdev->of_reset_n_cells = 1;
+ rcdev->of_xlate = mpfs_reset_xlate;
+ rcdev->nr_resets = MPFS_NUM_RESETS;
+
+ return devm_reset_controller_register(dev, rcdev);
+}
+
+static const struct auxiliary_device_id mpfs_reset_ids[] = {
+ {
+ .name = "clk_mpfs.reset-mpfs",
+ },
+ { }
+};
+MODULE_DEVICE_TABLE(auxiliary, mpfs_reset_ids);
+
+static struct auxiliary_driver mpfs_reset_driver = {
+ .probe = mpfs_reset_probe,
+ .id_table = mpfs_reset_ids,
+};
+
+module_auxiliary_driver(mpfs_reset_driver);
+
+MODULE_DESCRIPTION("Microchip PolarFire SoC Reset Driver");
+MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(MCHP_CLK_MPFS);
--
2.36.1