[PATCH v11 15/15] soc: amd: Add support for AMD Pensando SoC Controller

Brad Larson
2023-03-12T00:49:02Z

The Pensando SoC controller is a SPI connected companion device
that is present in all Pensando SoC board designs. The essential
board management registers are accessed on chip select 0 with
board mgmt IO support accessed using additional chip selects.

Signed-off-by: Brad Larson <blarson@amd.com>
---

v11 changes:
- Fix the compatible to be specific 'amd,pensando-elba-ctrl'
- Cast arguments flagged with a gcc-12.1.0 warning:
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202303061526.I8VPcR1M-lkp@intel.com/

v10 changes:
- Different driver implementation specific to this Pensando controller device.
- Moved to soc/amd directory under new name based on guidance. This driver is
of no use to any design other than all Pensando SoC based cards.
- Removed use of builtin_driver, can be built as a module.

v9 changes:
- Previously patch 14/17
- After the change to the device tree node and squashing
reset-cells into the parent simplified this to not use
any MFD API and move it to drivers/spi/pensando-sr.c.
- Change the naming to remove elba since this driver is common
for all Pensando SoC designs .
- Default yes SPI_PENSANDO_SR for ARCH_PENSANDO

---
drivers/soc/Kconfig | 1 +
drivers/soc/Makefile | 1 +
drivers/soc/amd/Kconfig | 16 ++
drivers/soc/amd/Makefile | 2 +
drivers/soc/amd/pensando-ctrl.c | 378 +++++++++++++++++++++++++
include/uapi/linux/amd-pensando-ctrl.h | 30 ++
6 files changed, 428 insertions(+)
create mode 100644 drivers/soc/amd/Kconfig
create mode 100644 drivers/soc/amd/Makefile
create mode 100644 drivers/soc/amd/pensando-ctrl.c
create mode 100644 include/uapi/linux/amd-pensando-ctrl.h

diff --git a/drivers/soc/Kconfig b/drivers/soc/Kconfig
index 4e176280113a..9e023f74e47c 100644
--- a/drivers/soc/Kconfig
+++ b/drivers/soc/Kconfig
@@ -2,6 +2,7 @@
menu "SOC (System On Chip) specific Drivers"

source "drivers/soc/actions/Kconfig"
+source "drivers/soc/amd/Kconfig"
source "drivers/soc/amlogic/Kconfig"
source "drivers/soc/apple/Kconfig"
source "drivers/soc/aspeed/Kconfig"
diff --git a/drivers/soc/Makefile b/drivers/soc/Makefile
index 3b0f9fb3b5c8..8914530f2721 100644
--- a/drivers/soc/Makefile
+++ b/drivers/soc/Makefile
@@ -4,6 +4,7 @@
#

obj-$(CONFIG_ARCH_ACTIONS) += actions/
+obj-y += amd/
obj-y += apple/
obj-y += aspeed/
obj-$(CONFIG_ARCH_AT91) += atmel/
diff --git a/drivers/soc/amd/Kconfig b/drivers/soc/amd/Kconfig
new file mode 100644
index 000000000000..9fc03de49f11
--- /dev/null
+++ b/drivers/soc/amd/Kconfig
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menu "AMD Pensando SoC drivers"
+
+config AMD_PENSANDO_CTRL
+ tristate "AMD Pensando SoC Controller"
+ depends on SPI_MASTER=y
+ depends on (ARCH_PENSANDO && OF) || COMPILE_TEST
+ default y if ARCH_PENSANDO
+ select REGMAP_SPI
+ select MFD_SYSCON
+ help
+ Enables AMD Pensando SoC controller device support. This is a SPI
+ attached companion device in all Pensando SoC board designs which
+ provides essential board control/status registers and management IO
+ support.
+endmenu
diff --git a/drivers/soc/amd/Makefile b/drivers/soc/amd/Makefile
new file mode 100644
index 000000000000..a2de0424f68d
--- /dev/null
+++ b/drivers/soc/amd/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_AMD_PENSANDO_CTRL) += pensando-ctrl.o
diff --git a/drivers/soc/amd/pensando-ctrl.c b/drivers/soc/amd/pensando-ctrl.c
new file mode 100644
index 000000000000..4f1b2b1f5092
--- /dev/null
+++ b/drivers/soc/amd/pensando-ctrl.c
@@ -0,0 +1,378 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * AMD Pensando SoC Controller
+ *
+ * Userspace interface and reset driver support for SPI connected Pensando SoC
+ * controller device. This device is present in all Pensando SoC designs and
+ * contains board control/status regsiters and management IO support.
+ *
+ * Copyright 2023 Advanced Micro Devices, Inc.
+ */
+
+#include <linux/cdev.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/reset-controller.h>
+#include <linux/spi/spi.h>
+#include <linux/amd-pensando-ctrl.h>
+
+struct penctrl_device {
+ struct spi_device *spi_dev;
+ struct reset_controller_dev rcdev;
+};
+
+static DEFINE_MUTEX(spi_lock);
+static dev_t penctrl_devt;
+static struct penctrl_device *penctrl;
+static struct class *penctrl_class;
+
+static long
+penctrl_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+ struct spi_transfer t[2] = { 0 };
+ struct penctrl_device *penctrl;
+ struct penctrl_spi_xfer *msg;
+ struct spi_device *spi_dev;
+ unsigned int num_msgs;
+ struct spi_message m;
+ u8 tx_buf[PENCTRL_MAX_MSG_LEN];
+ u8 rx_buf[PENCTRL_MAX_MSG_LEN];
+ u32 size;
+ int ret;
+
+ /* Check for a valid command */
+ if (_IOC_TYPE(cmd) != PENCTRL_IOC_MAGIC)
+ return -ENOTTY;
+
+ if (_IOC_NR(cmd) > PENCTRL_IOC_MAXNR)
+ return -ENOTTY;
+
+ if (_IOC_DIR(cmd) & _IOC_READ)
+ ret = !access_ok((void __user *)arg, _IOC_SIZE(cmd));
+ else if (_IOC_DIR(cmd) & _IOC_WRITE)
+ ret = !access_ok((void __user *)arg, _IOC_SIZE(cmd));
+
+ if (ret)
+ return -EFAULT;
+
+ /* Get a reference to the SPI device */
+ penctrl = filp->private_data;
+ if (!penctrl)
+ return -ESHUTDOWN;
+
+ spi_dev = spi_dev_get(penctrl->spi_dev);
+ if (!spi_dev)
+ return -ESHUTDOWN;
+
+ /* Verify and prepare spi message */
+ size = _IOC_SIZE(cmd);
+ if ((size % sizeof(struct penctrl_spi_xfer)) != 0) {
+ ret = -EINVAL;
+ goto done;
+ }
+ num_msgs = size / sizeof(struct penctrl_spi_xfer);
+ if (num_msgs == 0) {
+ ret = -EINVAL;
+ goto done;
+ }
+ msg = memdup_user((struct penctrl_spi_xfer __user *)arg, size);
+ if (!msg) {
+ ret = PTR_ERR(msg);
+ goto done;
+ }
+ if (msg->len > PENCTRL_MAX_MSG_LEN) {
+ ret = -EINVAL;
+ goto done;
+ }
+
+ t[0].tx_buf = tx_buf;
+ t[0].len = msg->len;
+ if (copy_from_user((void *)tx_buf, (void __user *)msg->tx_buf, msg->len)) {
+ ret = -EFAULT;
+ goto done;
+ }
+ if (num_msgs > 1) {
+ msg++;
+ if (msg->len > PENCTRL_MAX_MSG_LEN) {
+ ret = -EINVAL;
+ goto done;
+ }
+ t[1].rx_buf = rx_buf;
+ t[1].len = msg->len;
+ }
+ spi_message_init_with_transfers(&m, t, num_msgs);
+
+ /* Perform the transfer */
+ mutex_lock(&spi_lock);
+ ret = spi_sync(spi_dev, &m);
+ mutex_unlock(&spi_lock);
+
+ if (ret || (num_msgs == 1))
+ goto done;
+
+ if (copy_to_user((void __user *)msg->rx_buf, (void *)rx_buf, msg->len))
+ ret = -EFAULT;
+
+done:
+ spi_dev_put(spi_dev);
+ return ret;
+}
+
+static int penctrl_open(struct inode *inode, struct file *filp)
+{
+ struct spi_device *spi_dev;
+ u8 current_cs;
+
+ if (!penctrl)
+ return -ENODEV;
+
+ filp->private_data = penctrl;
+ current_cs = iminor(inode);
+ spi_dev = penctrl->spi_dev;
+ spi_dev->chip_select = current_cs;
+ spi_dev->cs_gpiod = spi_dev->controller->cs_gpiods[current_cs];
+ spi_setup(spi_dev);
+ stream_open(inode, filp);
+
+ return 0;
+}
+
+static int penctrl_release(struct inode *inode, struct file *filp)
+{
+ filp->private_data = NULL;
+ return 0;
+}
+
+static const struct file_operations penctrl_fops = {
+ .owner = THIS_MODULE,
+ .unlocked_ioctl = penctrl_ioctl,
+ .open = penctrl_open,
+ .release = penctrl_release,
+ .llseek = no_llseek,
+};
+
+static int penctrl_regs_read(struct penctrl_device *penctrl, u32 reg, u32 *val)
+{
+ struct spi_device *spi_dev = penctrl->spi_dev;
+ struct spi_transfer t[2] = { 0 };
+ struct spi_message m;
+ u8 txbuf[3];
+ u8 rxbuf[1];
+ int ret;
+
+ txbuf[0] = PENCTRL_SPI_CMD_REGRD;
+ txbuf[1] = reg;
+ txbuf[2] = 0x0;
+ t[0].tx_buf = txbuf;
+ t[0].len = 3;
+
+ rxbuf[0] = 0x0;
+ t[1].rx_buf = rxbuf;
+ t[1].len = 1;
+
+ spi_message_init_with_transfers(&m, t, ARRAY_SIZE(t));
+ ret = spi_sync(spi_dev, &m);
+ if (ret == 0)
+ *val = rxbuf[0];
+
+ return ret;
+}
+
+static int penctrl_regs_write(struct penctrl_device *penctrl, u32 reg, u32 val)
+{
+ struct spi_device *spi_dev = penctrl->spi_dev;
+ struct spi_transfer t[1] = { 0 };
+ struct spi_message m;
+ u8 txbuf[4];
+ int ret;
+
+ txbuf[0] = PENCTRL_SPI_CMD_REGWR;
+ txbuf[1] = reg;
+ txbuf[2] = val;
+ txbuf[3] = 0;
+
+ t[0].tx_buf = txbuf;
+ t[0].len = 4;
+ spi_message_init_with_transfers(&m, t, ARRAY_SIZE(t));
+ ret = spi_sync(spi_dev, &m);
+ return ret;
+}
+
+static int penctrl_reset_assert(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct penctrl_device *penctrl =
+ container_of(rcdev, struct penctrl_device, rcdev);
+ struct spi_device *spi_dev = penctrl->spi_dev;
+ unsigned int val;
+ int ret;
+
+ mutex_lock(&spi_lock);
+ spi_dev->chip_select = 0;
+ spi_dev->cs_gpiod = spi_dev->controller->cs_gpiods[0];
+ spi_setup(spi_dev);
+ ret = penctrl_regs_read(penctrl, PENCTRL_REG_CTRL0, &val);
+ if (ret) {
+ dev_err(&spi_dev->dev, "error reading ctrl0 reg\n");
+ goto done;
+ }
+
+ val |= BIT(6);
+ ret = penctrl_regs_write(penctrl, PENCTRL_REG_CTRL0, val);
+ if (ret)
+ dev_err(&spi_dev->dev, "error writing ctrl0 reg\n");
+
+done:
+ mutex_unlock(&spi_lock);
+ return ret;
+}
+
+static int penctrl_reset_deassert(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct penctrl_device *penctrl =
+ container_of(rcdev, struct penctrl_device, rcdev);
+ struct spi_device *spi_dev = penctrl->spi_dev;
+ unsigned int val;
+ int ret;
+
+ mutex_lock(&spi_lock);
+ spi_dev->chip_select = 0;
+ spi_dev->cs_gpiod = spi_dev->controller->cs_gpiods[0];
+ spi_setup(spi_dev);
+ ret = penctrl_regs_read(penctrl, PENCTRL_REG_CTRL0, &val);
+ if (ret) {
+ dev_err(&spi_dev->dev, "error reading ctrl0 reg\n");
+ goto done;
+ }
+
+ val &= ~BIT(6);
+ ret = penctrl_regs_write(penctrl, PENCTRL_REG_CTRL0, val);
+ if (ret)
+ dev_err(&spi_dev->dev, "error writing ctrl0 reg\n");
+
+done:
+ mutex_unlock(&spi_lock);
+ return ret;
+}
+
+static const struct reset_control_ops penctrl_reset_ops = {
+ .assert = penctrl_reset_assert,
+ .deassert = penctrl_reset_deassert,
+};
+
+static int penctrl_spi_probe(struct spi_device *spi_dev)
+{
+ struct device_node *np;
+ struct device *dev;
+ struct cdev *cdev;
+ u32 num_cs;
+ int ret;
+ u32 cs;
+
+ np = spi_dev->dev.parent->of_node;
+ ret = of_property_read_u32(np, "num-cs", &num_cs);
+ if (ret)
+ return dev_err_probe(&spi_dev->dev, ret,
+ "number of chip-selects not defined");
+
+ ret = alloc_chrdev_region(&penctrl_devt, 0, num_cs, "penctrl");
+ if (ret)
+ return dev_err_probe(&spi_dev->dev, ret,
+ "failed to alloc chrdev region\n");
+
+ penctrl_class = class_create(THIS_MODULE, "penctrl");
+ if (IS_ERR(penctrl_class)) {
+ unregister_chrdev(MAJOR(penctrl_devt), "penctrl");
+ return dev_err_probe(&spi_dev->dev, PTR_ERR(penctrl_class),
+ "failed to create class\n");
+ }
+
+ cdev = cdev_alloc();
+ if (!cdev) {
+ dev_err(&spi_dev->dev, "allocation of cdev failed");
+ ret = -ENOMEM;
+ goto cdev_failed;
+ }
+ cdev->owner = THIS_MODULE;
+ cdev_init(cdev, &penctrl_fops);
+
+ ret = cdev_add(cdev, penctrl_devt, num_cs);
+ if (ret) {
+ dev_err(&spi_dev->dev, "register of cdev failed");
+ goto cdev_delete;
+ }
+
+ /* Allocate driver data */
+ penctrl = kzalloc(sizeof(*penctrl), GFP_KERNEL);
+ if (!penctrl) {
+ ret = -ENOMEM;
+ dev_err(&spi_dev->dev, "allocate driver data failed");
+ goto cdev_delete;
+ }
+
+ penctrl->spi_dev = spi_dev;
+ mutex_init(&spi_lock);
+
+ /* Create a device for each chip select */
+ for (cs = 0; cs < num_cs; cs++) {
+ dev = device_create(penctrl_class,
+ &spi_dev->dev,
+ MKDEV(MAJOR(penctrl_devt), cs),
+ penctrl,
+ "penctrl0.%d",
+ cs);
+ if (IS_ERR(dev)) {
+ ret = IS_ERR(dev);
+ dev_err(&spi_dev->dev, "error creating device\n");
+ goto cdev_delete;
+ }
+ dev_dbg(&spi_dev->dev, "created device major %u, minor %d\n",
+ MAJOR(penctrl_devt), cs);
+ }
+
+ spi_set_drvdata(spi_dev, penctrl);
+
+ /* Register emmc hardware reset */
+ penctrl->rcdev.nr_resets = 1;
+ penctrl->rcdev.owner = THIS_MODULE;
+ penctrl->rcdev.dev = &spi_dev->dev;
+ penctrl->rcdev.ops = &penctrl_reset_ops;
+ penctrl->rcdev.of_node = spi_dev->dev.of_node;
+ ret = reset_controller_register(&penctrl->rcdev);
+ if (ret)
+ return dev_err_probe(&spi_dev->dev, ret,
+ "failed to register reset controller\n");
+ return ret;
+
+cdev_delete:
+ cdev_del(cdev);
+cdev_failed:
+ device_destroy(penctrl_class, penctrl_devt);
+ return ret;
+}
+
+static const struct of_device_id penctrl_dt_match[] = {
+ { .compatible = "amd,pensando-elba-ctrl" },
+ { /* sentinel */ }
+};
+
+static struct spi_driver penctrl_spi_driver = {
+ .probe = penctrl_spi_probe,
+ .driver = {
+ .name = "pensando-ctrl",
+ .of_match_table = penctrl_dt_match,
+ },
+};
+module_spi_driver(penctrl_spi_driver);
+
+MODULE_AUTHOR("Brad Larson <blarson@amd.com>");
+MODULE_DESCRIPTION("AMD Pensando SoC Controller via SPI");
+MODULE_LICENSE("GPL");
diff --git a/include/uapi/linux/amd-pensando-ctrl.h b/include/uapi/linux/amd-pensando-ctrl.h
new file mode 100644
index 000000000000..0a6caf3b764c
--- /dev/null
+++ b/include/uapi/linux/amd-pensando-ctrl.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Userspace interface for /dev/penctrl
+ *
+ * This file can be used by applications that need to communicate
+ * with the AMD Pensando SoC controller device via the ioctl interface.
+ */
+#ifndef _UAPI_LINUX_AMD_PENSANDO_CTRL_H
+#define _UAPI_LINUX_AMD_PENSANDO_CTRL_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+
+#define PENCTRL_SPI_CMD_REGRD 0x0b
+#define PENCTRL_SPI_CMD_REGWR 0x02
+#define PENCTRL_IOC_MAGIC 'k'
+#define PENCTRL_IOC_MAXNR 0
+#define PENCTRL_MAX_MSG_LEN 16
+#define PENCTRL_MAX_REG 0xff
+#define PENCTRL_REG_CTRL0 0x10
+
+struct penctrl_spi_xfer {
+ __u64 tx_buf;
+ __u64 rx_buf;
+ __u32 len;
+ __u32 speed_hz;
+ __u64 compat;
+};
+
+#endif /* _UAPI_LINUX_AMD_PENSANDO_CTRL_H */
--
2.17.1