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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * OPAL Operator Panel Display Driver4 *5 * Copyright 2016, Suraj Jitindar Singh, IBM Corporation.6 */7 8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt9 10#include <linux/init.h>11#include <linux/module.h>12#include <linux/kernel.h>13#include <linux/fs.h>14#include <linux/device.h>15#include <linux/errno.h>16#include <linux/mutex.h>17#include <linux/of.h>18#include <linux/slab.h>19#include <linux/platform_device.h>20#include <linux/miscdevice.h>21 22#include <asm/opal.h>23 24/*25 * This driver creates a character device (/dev/op_panel) which exposes the26 * operator panel (character LCD display) on IBM Power Systems machines27 * with FSPs.28 * A character buffer written to the device will be displayed on the29 * operator panel.30 */31 32static DEFINE_MUTEX(oppanel_mutex);33 34static u32 num_lines, oppanel_size;35static oppanel_line_t *oppanel_lines;36static char *oppanel_data;37 38static loff_t oppanel_llseek(struct file *filp, loff_t offset, int whence)39{40 return fixed_size_llseek(filp, offset, whence, oppanel_size);41}42 43static ssize_t oppanel_read(struct file *filp, char __user *userbuf, size_t len,44 loff_t *f_pos)45{46 return simple_read_from_buffer(userbuf, len, f_pos, oppanel_data,47 oppanel_size);48}49 50static int __op_panel_update_display(void)51{52 struct opal_msg msg;53 int rc, token;54 55 token = opal_async_get_token_interruptible();56 if (token < 0) {57 if (token != -ERESTARTSYS)58 pr_debug("Couldn't get OPAL async token [token=%d]\n",59 token);60 return token;61 }62 63 rc = opal_write_oppanel_async(token, oppanel_lines, num_lines);64 switch (rc) {65 case OPAL_ASYNC_COMPLETION:66 rc = opal_async_wait_response(token, &msg);67 if (rc) {68 pr_debug("Failed to wait for async response [rc=%d]\n",69 rc);70 break;71 }72 rc = opal_get_async_rc(msg);73 if (rc != OPAL_SUCCESS) {74 pr_debug("OPAL async call returned failed [rc=%d]\n",75 rc);76 break;77 }78 break;79 case OPAL_SUCCESS:80 break;81 default:82 pr_debug("OPAL write op-panel call failed [rc=%d]\n", rc);83 }84 85 opal_async_release_token(token);86 return rc;87}88 89static ssize_t oppanel_write(struct file *filp, const char __user *userbuf,90 size_t len, loff_t *f_pos)91{92 loff_t f_pos_prev = *f_pos;93 ssize_t ret;94 int rc;95 96 if (!*f_pos)97 memset(oppanel_data, ' ', oppanel_size);98 else if (*f_pos >= oppanel_size)99 return -EFBIG;100 101 ret = simple_write_to_buffer(oppanel_data, oppanel_size, f_pos, userbuf,102 len);103 if (ret > 0) {104 rc = __op_panel_update_display();105 if (rc != OPAL_SUCCESS) {106 pr_err_ratelimited("OPAL call failed to write to op panel display [rc=%d]\n",107 rc);108 *f_pos = f_pos_prev;109 return -EIO;110 }111 }112 return ret;113}114 115static int oppanel_open(struct inode *inode, struct file *filp)116{117 if (!mutex_trylock(&oppanel_mutex)) {118 pr_debug("Device Busy\n");119 return -EBUSY;120 }121 return 0;122}123 124static int oppanel_release(struct inode *inode, struct file *filp)125{126 mutex_unlock(&oppanel_mutex);127 return 0;128}129 130static const struct file_operations oppanel_fops = {131 .owner = THIS_MODULE,132 .llseek = oppanel_llseek,133 .read = oppanel_read,134 .write = oppanel_write,135 .open = oppanel_open,136 .release = oppanel_release137};138 139static struct miscdevice oppanel_dev = {140 .minor = MISC_DYNAMIC_MINOR,141 .name = "op_panel",142 .fops = &oppanel_fops143};144 145static int oppanel_probe(struct platform_device *pdev)146{147 struct device_node *np = pdev->dev.of_node;148 u32 line_len;149 int rc, i;150 151 rc = of_property_read_u32(np, "#length", &line_len);152 if (rc) {153 pr_err_ratelimited("Operator panel length property not found\n");154 return rc;155 }156 rc = of_property_read_u32(np, "#lines", &num_lines);157 if (rc) {158 pr_err_ratelimited("Operator panel lines property not found\n");159 return rc;160 }161 oppanel_size = line_len * num_lines;162 163 pr_devel("Operator panel of size %u found with %u lines of length %u\n",164 oppanel_size, num_lines, line_len);165 166 oppanel_data = kcalloc(oppanel_size, sizeof(*oppanel_data), GFP_KERNEL);167 if (!oppanel_data)168 return -ENOMEM;169 170 oppanel_lines = kcalloc(num_lines, sizeof(oppanel_line_t), GFP_KERNEL);171 if (!oppanel_lines) {172 rc = -ENOMEM;173 goto free_oppanel_data;174 }175 176 memset(oppanel_data, ' ', oppanel_size);177 for (i = 0; i < num_lines; i++) {178 oppanel_lines[i].line_len = cpu_to_be64(line_len);179 oppanel_lines[i].line = cpu_to_be64(__pa(&oppanel_data[i *180 line_len]));181 }182 183 rc = misc_register(&oppanel_dev);184 if (rc) {185 pr_err_ratelimited("Failed to register as misc device\n");186 goto free_oppanel;187 }188 189 return 0;190 191free_oppanel:192 kfree(oppanel_lines);193free_oppanel_data:194 kfree(oppanel_data);195 return rc;196}197 198static void oppanel_remove(struct platform_device *pdev)199{200 misc_deregister(&oppanel_dev);201 kfree(oppanel_lines);202 kfree(oppanel_data);203}204 205static const struct of_device_id oppanel_match[] = {206 { .compatible = "ibm,opal-oppanel" },207 { },208};209 210static struct platform_driver oppanel_driver = {211 .driver = {212 .name = "powernv-op-panel",213 .of_match_table = oppanel_match,214 },215 .probe = oppanel_probe,216 .remove_new = oppanel_remove,217};218 219module_platform_driver(oppanel_driver);220 221MODULE_DEVICE_TABLE(of, oppanel_match);222MODULE_LICENSE("GPL v2");223MODULE_DESCRIPTION("PowerNV Operator Panel LCD Display Driver");224MODULE_AUTHOR("Suraj Jitindar Singh <sjitindarsingh@gmail.com>");225