path: root/drivers/fsi/fsi-occ.c

// SPDX-License-Identifier: GPL-2.0

#include <linux/device.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/fsi-sbefifo.h>
#include <linux/gfp.h>
#include <linux/idr.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/fsi-occ.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <asm/unaligned.h>

#define OCC_SRAM_BYTES		4096
#define OCC_CMD_DATA_BYTES	4090
#define OCC_RESP_DATA_BYTES	4089

#define OCC_P9_SRAM_CMD_ADDR	0xFFFBE000
#define OCC_P9_SRAM_RSP_ADDR	0xFFFBF000

#define OCC_P10_SRAM_CMD_ADDR	0xFFFFD000
#define OCC_P10_SRAM_RSP_ADDR	0xFFFFE000

#define OCC_P10_SRAM_MODE	0x58	/* Normal mode, OCB channel 2 */

/*
 * Assume we don't have much FFDC, if we do we'll overflow and
 * fail the command. This needs to be big enough for simple
 * commands as well.
 */
#define OCC_SBE_STATUS_WORDS	32

#define OCC_TIMEOUT_MS		1000
#define OCC_CMD_IN_PRG_WAIT_MS	50

enum versions { occ_p9, occ_p10 };

struct occ {
	struct device *dev;
	struct device *sbefifo;
	char name[32];
	int idx;
	enum versions version;
	struct miscdevice mdev;
	struct mutex occ_lock;
};

#define to_occ(x)	container_of((x), struct occ, mdev)

struct occ_response {
	u8 seq_no;
	u8 cmd_type;
	u8 return_status;
	__be16 data_length;
	u8 data[OCC_RESP_DATA_BYTES + 2];	/* two bytes checksum */
} __packed;

struct occ_client {
	struct occ *occ;
	struct mutex lock;
	size_t data_size;
	size_t read_offset;
	u8 *buffer;
};

#define to_client(x)	container_of((x), struct occ_client, xfr)

static DEFINE_IDA(occ_ida);

static int occ_open(struct inode *inode, struct file *file)
{
	struct occ_client *client = kzalloc(sizeof(*client), GFP_KERNEL);
	struct miscdevice *mdev = file->private_data;
	struct occ *occ = to_occ(mdev);

	if (!client)
		return -ENOMEM;

	client->buffer = (u8 *)__get_free_page(GFP_KERNEL);
	if (!client->buffer) {
		kfree(client);
		return -ENOMEM;
	}

	client->occ = occ;
	mutex_init(&client->lock);
	file->private_data = client;

	/* We allocate a 1-page buffer, make sure it all fits */
	BUILD_BUG_ON((OCC_CMD_DATA_BYTES + 3) > PAGE_SIZE);
	BUILD_BUG_ON((OCC_RESP_DATA_BYTES + 7) > PAGE_SIZE);

	return 0;
}

static ssize_t occ_read(struct file *file, char __user *buf, size_t len,
			loff_t *offset)
{
	struct occ_client *client = file->private_data;
	ssize_t rc = 0;

	if (!client)
		return -ENODEV;

	if (len > OCC_SRAM_BYTES)
		return -EINVAL;

	mutex_lock(&client->lock);

	/* This should not be possible ... */
	if (WARN_ON_ONCE(client->read_offset > client->data_size)) {
		rc = -EIO;
		goto done;
	}

	/* Grab how much data we have to read */
	rc = min(len, client->data_size - client->read_offset);
	if (copy_to_user(buf, client->buffer + client->read_offset, rc))
		rc = -EFAULT;
	else
		client->read_offset += rc;

 done:
	mutex_unlock(&client->lock);

	return rc;
}

static ssize_t occ_write(struct file *file, const char __user *buf,
			 size_t len, loff_t *offset)
{
	struct occ_client *client = file->private_data;
	size_t rlen, data_length;
	u16 checksum = 0;
	ssize_t rc, i;
	u8 *cmd;

	if (!client)
		return -ENODEV;

	if (len > (OCC_CMD_DATA_BYTES + 3) || len < 3)
		return -EINVAL;

	mutex_lock(&client->lock);

	/* Construct the command */
	cmd = client->buffer;

	/* Sequence number (we could increment and compare with response) */
	cmd[0] = 1;

	/*
	 * Copy the user command (assume user data follows the occ command
	 * format)
	 * byte 0: command type
	 * bytes 1-2: data length (msb first)
	 * bytes 3-n: data
	 */
	if (copy_from_user(&cmd[1], buf, len)) {
		rc = -EFAULT;
		goto done;
	}

	/* Extract data length */
	data_length = (cmd[2] << 8) + cmd[3];
	if (data_length > OCC_CMD_DATA_BYTES) {
		rc = -EINVAL;
		goto done;
	}

	/* Calculate checksum */
	for (i = 0; i < data_length + 4; ++i)
		checksum += cmd[i];

	cmd[data_length + 4] = checksum >> 8;
	cmd[data_length + 5] = checksum & 0xFF;

	/* Submit command */
	rlen = PAGE_SIZE;
	rc = fsi_occ_submit(client->occ->dev, cmd, data_length + 6, cmd,
			    &rlen);
	if (rc)
		goto done;

	/* Set read tracking data */
	client->data_size = rlen;
	client->read_offset = 0;

	/* Done */
	rc = len;

 done:
	mutex_unlock(&client->lock);

	return rc;
}

static int occ_release(struct inode *inode, struct file *file)
{
	struct occ_client *client = file->private_data;

	free_page((unsigned long)client->buffer);
	kfree(client);

	return 0;
}

static const struct file_operations occ_fops = {
	.owner = THIS_MODULE,
	.open = occ_open,
	.read = occ_read,
	.write = occ_write,
	.release = occ_release,
};

static int occ_verify_checksum(struct occ_response *resp, u16 data_length)
{
	/* Fetch the two bytes after the data for the checksum. */
	u16 checksum_resp = get_unaligned_be16(&resp->data[data_length]);
	u16 checksum;
	u16 i;

	checksum = resp->seq_no;
	checksum += resp->cmd_type;
	checksum += resp->return_status;
	checksum += (data_length >> 8) + (data_length & 0xFF);

	for (i = <