diff options
Diffstat (limited to 'drivers/char/powernv-op-panel.c')
| -rw-r--r-- | drivers/char/powernv-op-panel.c | 225 |
1 files changed, 225 insertions, 0 deletions
diff --git a/drivers/char/powernv-op-panel.c b/drivers/char/powernv-op-panel.c new file mode 100644 index 000000000..3c99696b1 --- /dev/null +++ b/drivers/char/powernv-op-panel.c @@ -0,0 +1,225 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * OPAL Operator Panel Display Driver + * + * Copyright 2016, Suraj Jitindar Singh, IBM Corporation. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/init.h> +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/fs.h> +#include <linux/device.h> +#include <linux/errno.h> +#include <linux/mutex.h> +#include <linux/of.h> +#include <linux/slab.h> +#include <linux/platform_device.h> +#include <linux/miscdevice.h> + +#include <asm/opal.h> + +/* + * This driver creates a character device (/dev/op_panel) which exposes the + * operator panel (character LCD display) on IBM Power Systems machines + * with FSPs. + * A character buffer written to the device will be displayed on the + * operator panel. + */ + +static DEFINE_MUTEX(oppanel_mutex); + +static u32 num_lines, oppanel_size; +static oppanel_line_t *oppanel_lines; +static char *oppanel_data; + +static loff_t oppanel_llseek(struct file *filp, loff_t offset, int whence) +{ + return fixed_size_llseek(filp, offset, whence, oppanel_size); +} + +static ssize_t oppanel_read(struct file *filp, char __user *userbuf, size_t len, + loff_t *f_pos) +{ + return simple_read_from_buffer(userbuf, len, f_pos, oppanel_data, + oppanel_size); +} + +static int __op_panel_update_display(void) +{ + struct opal_msg msg; + int rc, token; + + token = opal_async_get_token_interruptible(); + if (token < 0) { + if (token != -ERESTARTSYS) + pr_debug("Couldn't get OPAL async token [token=%d]\n", + token); + return token; + } + + rc = opal_write_oppanel_async(token, oppanel_lines, num_lines); + switch (rc) { + case OPAL_ASYNC_COMPLETION: + rc = opal_async_wait_response(token, &msg); + if (rc) { + pr_debug("Failed to wait for async response [rc=%d]\n", + rc); + break; + } + rc = opal_get_async_rc(msg); + if (rc != OPAL_SUCCESS) { + pr_debug("OPAL async call returned failed [rc=%d]\n", + rc); + break; + } + break; + case OPAL_SUCCESS: + break; + default: + pr_debug("OPAL write op-panel call failed [rc=%d]\n", rc); + } + + opal_async_release_token(token); + return rc; +} + +static ssize_t oppanel_write(struct file *filp, const char __user *userbuf, + size_t len, loff_t *f_pos) +{ + loff_t f_pos_prev = *f_pos; + ssize_t ret; + int rc; + + if (!*f_pos) + memset(oppanel_data, ' ', oppanel_size); + else if (*f_pos >= oppanel_size) + return -EFBIG; + + ret = simple_write_to_buffer(oppanel_data, oppanel_size, f_pos, userbuf, + len); + if (ret > 0) { + rc = __op_panel_update_display(); + if (rc != OPAL_SUCCESS) { + pr_err_ratelimited("OPAL call failed to write to op panel display [rc=%d]\n", + rc); + *f_pos = f_pos_prev; + return -EIO; + } + } + return ret; +} + +static int oppanel_open(struct inode *inode, struct file *filp) +{ + if (!mutex_trylock(&oppanel_mutex)) { + pr_debug("Device Busy\n"); + return -EBUSY; + } + return 0; +} + +static int oppanel_release(struct inode *inode, struct file *filp) +{ + mutex_unlock(&oppanel_mutex); + return 0; +} + +static const struct file_operations oppanel_fops = { + .owner = THIS_MODULE, + .llseek = oppanel_llseek, + .read = oppanel_read, + .write = oppanel_write, + .open = oppanel_open, + .release = oppanel_release +}; + +static struct miscdevice oppanel_dev = { + .minor = MISC_DYNAMIC_MINOR, + .name = "op_panel", + .fops = &oppanel_fops +}; + +static int oppanel_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + u32 line_len; + int rc, i; + + rc = of_property_read_u32(np, "#length", &line_len); + if (rc) { + pr_err_ratelimited("Operator panel length property not found\n"); + return rc; + } + rc = of_property_read_u32(np, "#lines", &num_lines); + if (rc) { + pr_err_ratelimited("Operator panel lines property not found\n"); + return rc; + } + oppanel_size = line_len * num_lines; + + pr_devel("Operator panel of size %u found with %u lines of length %u\n", + oppanel_size, num_lines, line_len); + + oppanel_data = kcalloc(oppanel_size, sizeof(*oppanel_data), GFP_KERNEL); + if (!oppanel_data) + return -ENOMEM; + + oppanel_lines = kcalloc(num_lines, sizeof(oppanel_line_t), GFP_KERNEL); + if (!oppanel_lines) { + rc = -ENOMEM; + goto free_oppanel_data; + } + + memset(oppanel_data, ' ', oppanel_size); + for (i = 0; i < num_lines; i++) { + oppanel_lines[i].line_len = cpu_to_be64(line_len); + oppanel_lines[i].line = cpu_to_be64(__pa(&oppanel_data[i * + line_len])); + } + + rc = misc_register(&oppanel_dev); + if (rc) { + pr_err_ratelimited("Failed to register as misc device\n"); + goto free_oppanel; + } + + return 0; + +free_oppanel: + kfree(oppanel_lines); +free_oppanel_data: + kfree(oppanel_data); + return rc; +} + +static int oppanel_remove(struct platform_device *pdev) +{ + misc_deregister(&oppanel_dev); + kfree(oppanel_lines); + kfree(oppanel_data); + return 0; +} + +static const struct of_device_id oppanel_match[] = { + { .compatible = "ibm,opal-oppanel" }, + { }, +}; + +static struct platform_driver oppanel_driver = { + .driver = { + .name = "powernv-op-panel", + .of_match_table = oppanel_match, + }, + .probe = oppanel_probe, + .remove = oppanel_remove, +}; + +module_platform_driver(oppanel_driver); + +MODULE_DEVICE_TABLE(of, oppanel_match); +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("PowerNV Operator Panel LCD Display Driver"); +MODULE_AUTHOR("Suraj Jitindar Singh <sjitindarsingh@gmail.com>"); |