[PATCH v6 15/17] reset: elbasr: Add AMD Pensando Elba SR Reset Controller

[Brad Larson <brad@pensando.io>]

From: Brad Larson <blarson@amd.com>

This patch adds the reset controller functionality for the
AMD Pensando Elba System Resource Chip.

Signed-off-by: Brad Larson <blarson@amd.com>
---
 drivers/reset/Kconfig        |  9 +++++
 drivers/reset/Makefile       |  1 +
 drivers/reset/reset-elbasr.c | 77 ++++++++++++++++++++++++++++++++++++
 3 files changed, 87 insertions(+)
 create mode 100644 drivers/reset/reset-elbasr.c

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 806773e88832..04b700c90ce4 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -66,6 +66,15 @@ config RESET_BRCMSTB_RESCAL
 	  This enables the RESCAL reset controller for SATA, PCIe0, or PCIe1 on
 	  BCM7216.
 
+config RESET_ELBASR
+	tristate "Pensando Elba System Resource reset controller"
+	depends on MFD_PENSANDO_ELBASR || COMPILE_TEST
+	help
+	  This option enables support for the external reset functions
+	  on the Pensando Elba System Resource Chip.  Reset control
+	  of peripherals is accessed over SPI to the system resource
+	  chip device registers using CS0.
+
 config RESET_HSDK
 	bool "Synopsys HSDK Reset Driver"
 	depends on HAS_IOMEM
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index cd5cf8e7c6a7..9e6b095ee63a 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_RESET_BCM6345) += reset-bcm6345.o
 obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
 obj-$(CONFIG_RESET_BRCMSTB) += reset-brcmstb.o
 obj-$(CONFIG_RESET_BRCMSTB_RESCAL) += reset-brcmstb-rescal.o
+obj-$(CONFIG_RESET_ELBASR) += reset-elbasr.o
 obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o
 obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
 obj-$(CONFIG_RESET_INTEL_GW) += reset-intel-gw.o
diff --git a/drivers/reset/reset-elbasr.c b/drivers/reset/reset-elbasr.c
new file mode 100644
index 000000000000..ab5d49f5e6a7
--- /dev/null
+++ b/drivers/reset/reset-elbasr.c
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2022 Advanced Micro Devices, Inc.
+ */
+
+#include <linux/err.h>
+#include <linux/mfd/pensando-elbasr.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+
+struct elbasr_reset {
+	struct reset_controller_dev rcdev;
+	struct regmap *regmap;
+};
+
+static inline struct elbasr_reset *to_elbasr_rst(struct reset_controller_dev *rc)
+{
+	return container_of(rc, struct elbasr_reset, rcdev);
+}
+
+static int elbasr_reset_assert(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	struct elbasr_reset *elbar = to_elbasr_rst(rcdev);
+
+	return regmap_update_bits(elbar->regmap, ELBASR_CTRL0_REG, BIT(6), BIT(6));
+}
+
+static int elbasr_reset_deassert(struct reset_controller_dev *rcdev,
+				 unsigned long id)
+{
+	struct elbasr_reset *elbar = to_elbasr_rst(rcdev);
+
+	return regmap_update_bits(elbar->regmap, ELBASR_CTRL0_REG, BIT(6), 0);
+}
+
+static const struct reset_control_ops elbasr_reset_ops = {
+	.assert	= elbasr_reset_assert,
+	.deassert = elbasr_reset_deassert,
+};
+
+static int elbasr_reset_probe(struct platform_device *pdev)
+{
+	struct elbasr_data *elbasr = dev_get_drvdata(pdev->dev.parent);
+	struct elbasr_reset *elbar;
+
+	elbar = devm_kzalloc(&pdev->dev, sizeof(struct elbasr_reset),
+			     GFP_KERNEL);
+	if (!elbar)
+		return -ENOMEM;
+
+	elbar->rcdev.owner = THIS_MODULE;
+	elbar->rcdev.nr_resets = ELBASR_NR_RESETS;
+	elbar->rcdev.ops = &elbasr_reset_ops;
+	elbar->rcdev.of_node = pdev->dev.of_node;
+	elbar->regmap = elbasr->elbasr_regs;
+
+	platform_set_drvdata(pdev, elbar);
+
+	return devm_reset_controller_register(&pdev->dev, &elbar->rcdev);
+}
+
+static const struct of_device_id elba_reset_dt_match[] = {
+	{ .compatible = "amd,pensando-elbasr-reset", },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver elbasr_reset_driver = {
+	.probe	= elbasr_reset_probe,
+	.driver = {
+		.name = "pensando_elbasr_reset",
+		.of_match_table	= elba_reset_dt_match,
+	},
+};
+builtin_platform_driver(elbasr_reset_driver);
-- 
2.17.1