/* * 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; } 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>");