1// SPDX-License-Identifier: MIT
  2/*
  3 * Permission is hereby granted, free of charge, to any person obtaining a
  4 * copy of this software and associated documentation files (the
  5 * "Software"), to deal in the Software without restriction, including
  6 * without limitation the rights to use, copy, modify, merge, publish,
  7 * distribute, sub license, and/or sell copies of the Software, and to
  8 * permit persons to whom the Software is furnished to do so, subject to
  9 * the following conditions:
 10 *
 11 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 12 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 13 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 14 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
 15 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 16 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 17 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 18 *
 19 * The above copyright notice and this permission notice (including the
 20 * next paragraph) shall be included in all copies or substantial portions
 21 * of the Software.
 22 */
 23
 24#include <linux/i2c-algo-bit.h>
 25#include <linux/i2c.h>
 26
 27#include <drm/drm_managed.h>
 28#include <drm/drm_print.h>
 29
 30#include "ast_ddc.h"
 31#include "ast_drv.h"
 32
 33struct ast_ddc {
 34	struct ast_device *ast;
 35
 36	struct i2c_algo_bit_data bit;
 37	struct i2c_adapter adapter;
 38};
 39
 40static void ast_ddc_algo_bit_data_setsda(void *data, int state)
 41{
 42	struct ast_ddc *ddc = data;
 43	struct ast_device *ast = ddc->ast;
 44	int i;
 45	u8 ujcrb7, jtemp;
 46
 47	for (i = 0; i < 0x10000; i++) {
 48		ujcrb7 = ((state & 0x01) ? 0 : 1) << 2;
 49		ast_set_index_reg_mask(ast, AST_IO_VGACRI, 0xb7, 0xf1, ujcrb7);
 50		jtemp = ast_get_index_reg_mask(ast, AST_IO_VGACRI, 0xb7, 0x04);
 51		if (ujcrb7 == jtemp)
 52			break;
 53	}
 54}
 55
 56static void ast_ddc_algo_bit_data_setscl(void *data, int state)
 57{
 58	struct ast_ddc *ddc = data;
 59	struct ast_device *ast = ddc->ast;
 60	int i;
 61	u8 ujcrb7, jtemp;
 62
 63	for (i = 0; i < 0x10000; i++) {
 64		ujcrb7 = ((state & 0x01) ? 0 : 1);
 65		ast_set_index_reg_mask(ast, AST_IO_VGACRI, 0xb7, 0xf4, ujcrb7);
 66		jtemp = ast_get_index_reg_mask(ast, AST_IO_VGACRI, 0xb7, 0x01);
 67		if (ujcrb7 == jtemp)
 68			break;
 69	}
 70}
 71
 72static int ast_ddc_algo_bit_data_pre_xfer(struct i2c_adapter *adapter)
 73{
 74	struct ast_ddc *ddc = i2c_get_adapdata(adapter);
 75	struct ast_device *ast = ddc->ast;
 76
 77	/*
 78	 * Protect access to I/O registers from concurrent modesetting
 79	 * by acquiring the I/O-register lock.
 80	 */
 81	mutex_lock(&ast->modeset_lock);
 82
 83	return 0;
 84}
 85
 86static void ast_ddc_algo_bit_data_post_xfer(struct i2c_adapter *adapter)
 87{
 88	struct ast_ddc *ddc = i2c_get_adapdata(adapter);
 89	struct ast_device *ast = ddc->ast;
 90
 91	mutex_unlock(&ast->modeset_lock);
 92}
 93
 94static int ast_ddc_algo_bit_data_getsda(void *data)
 95{
 96	struct ast_ddc *ddc = data;
 97	struct ast_device *ast = ddc->ast;
 98	uint32_t val, val2, count, pass;
 99
100	count = 0;
101	pass = 0;
102	val = (ast_get_index_reg_mask(ast, AST_IO_VGACRI, 0xb7, 0x20) >> 5) & 0x01;
103	do {
104		val2 = (ast_get_index_reg_mask(ast, AST_IO_VGACRI, 0xb7, 0x20) >> 5) & 0x01;
105		if (val == val2) {
106			pass++;
107		} else {
108			pass = 0;
109			val = (ast_get_index_reg_mask(ast, AST_IO_VGACRI, 0xb7, 0x20) >> 5) & 0x01;
110		}
111	} while ((pass < 5) && (count++ < 0x10000));
112
113	return val & 1 ? 1 : 0;
114}
115
116static int ast_ddc_algo_bit_data_getscl(void *data)
117{
118	struct ast_ddc *ddc = data;
119	struct ast_device *ast = ddc->ast;
120	uint32_t val, val2, count, pass;
121
122	count = 0;
123	pass = 0;
124	val = (ast_get_index_reg_mask(ast, AST_IO_VGACRI, 0xb7, 0x10) >> 4) & 0x01;
125	do {
126		val2 = (ast_get_index_reg_mask(ast, AST_IO_VGACRI, 0xb7, 0x10) >> 4) & 0x01;
127		if (val == val2) {
128			pass++;
129		} else {
130			pass = 0;
131			val = (ast_get_index_reg_mask(ast, AST_IO_VGACRI, 0xb7, 0x10) >> 4) & 0x01;
132		}
133	} while ((pass < 5) && (count++ < 0x10000));
134
135	return val & 1 ? 1 : 0;
136}
137
138static void ast_ddc_release(struct drm_device *dev, void *res)
139{
140	struct ast_ddc *ddc = res;
141
142	i2c_del_adapter(&ddc->adapter);
143}
144
145struct i2c_adapter *ast_ddc_create(struct ast_device *ast)
146{
147	struct drm_device *dev = &ast->base;
148	struct ast_ddc *ddc;
149	struct i2c_adapter *adapter;
150	struct i2c_algo_bit_data *bit;
151	int ret;
152
153	ddc = drmm_kzalloc(dev, sizeof(*ddc), GFP_KERNEL);
154	if (!ddc)
155		return ERR_PTR(-ENOMEM);
156	ddc->ast = ast;
157
158	bit = &ddc->bit;
159	bit->data = ddc;
160	bit->setsda = ast_ddc_algo_bit_data_setsda;
161	bit->setscl = ast_ddc_algo_bit_data_setscl;
162	bit->getsda = ast_ddc_algo_bit_data_getsda;
163	bit->getscl = ast_ddc_algo_bit_data_getscl;
164	bit->pre_xfer = ast_ddc_algo_bit_data_pre_xfer;
165	bit->post_xfer = ast_ddc_algo_bit_data_post_xfer;
166	bit->udelay = 20;
167	bit->timeout = usecs_to_jiffies(2200);
168
169	adapter = &ddc->adapter;
170	adapter->owner = THIS_MODULE;
171	adapter->algo_data = bit;
172	adapter->dev.parent = dev->dev;
173	snprintf(adapter->name, sizeof(adapter->name), "AST DDC bus");
174	i2c_set_adapdata(adapter, ddc);
175
176	ret = i2c_bit_add_bus(adapter);
177	if (ret) {
178		drm_err(dev, "Failed to register bit i2c\n");
179		return ERR_PTR(ret);
180	}
181
182	ret = drmm_add_action_or_reset(dev, ast_ddc_release, ddc);
183	if (ret)
184		return ERR_PTR(ret);
185
186	return &ddc->adapter;
187}