lsdc_i2c.c

  1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 * Copyright (C) 2023 Loongson Technology Corporation Limited
  4 */
  5
  6#include <drm/drm_managed.h>
  7#include <drm/drm_print.h>
  8
  9#include "lsdc_drv.h"
 10#include "lsdc_output.h"
 11
 12/*
 13 * __lsdc_gpio_i2c_set - set the state of a gpio pin indicated by mask
 14 * @mask: gpio pin mask
 15 * @state: "0" for low, "1" for high
 16 */
 17static void __lsdc_gpio_i2c_set(struct lsdc_i2c * const li2c, int mask, int state)
 18{
 19	struct lsdc_device *ldev = to_lsdc(li2c->ddev);
 20	unsigned long flags;
 21	u8 val;
 22
 23	spin_lock_irqsave(&ldev->reglock, flags);
 24
 25	if (state) {
 26		/*
 27		 * Setting this pin as input directly, write 1 for input.
 28		 * The external pull-up resistor will pull the level up
 29		 */
 30		val = readb(li2c->dir_reg);
 31		val |= mask;
 32		writeb(val, li2c->dir_reg);
 33	} else {
 34		/* First set this pin as output, write 0 for output */
 35		val = readb(li2c->dir_reg);
 36		val &= ~mask;
 37		writeb(val, li2c->dir_reg);
 38
 39		/* Then, make this pin output 0 */
 40		val = readb(li2c->dat_reg);
 41		val &= ~mask;
 42		writeb(val, li2c->dat_reg);
 43	}
 44
 45	spin_unlock_irqrestore(&ldev->reglock, flags);
 46}
 47
 48/*
 49 * __lsdc_gpio_i2c_get - read value back from the gpio pin indicated by mask
 50 * @mask: gpio pin mask
 51 * return "0" for low, "1" for high
 52 */
 53static int __lsdc_gpio_i2c_get(struct lsdc_i2c * const li2c, int mask)
 54{
 55	struct lsdc_device *ldev = to_lsdc(li2c->ddev);
 56	unsigned long flags;
 57	u8 val;
 58
 59	spin_lock_irqsave(&ldev->reglock, flags);
 60
 61	/* First set this pin as input */
 62	val = readb(li2c->dir_reg);
 63	val |= mask;
 64	writeb(val, li2c->dir_reg);
 65
 66	/* Then get level state from this pin */
 67	val = readb(li2c->dat_reg);
 68
 69	spin_unlock_irqrestore(&ldev->reglock, flags);
 70
 71	return (val & mask) ? 1 : 0;
 72}
 73
 74static void lsdc_gpio_i2c_set_sda(void *i2c, int state)
 75{
 76	struct lsdc_i2c * const li2c = (struct lsdc_i2c *)i2c;
 77	/* set state on the li2c->sda pin */
 78	return __lsdc_gpio_i2c_set(li2c, li2c->sda, state);
 79}
 80
 81static void lsdc_gpio_i2c_set_scl(void *i2c, int state)
 82{
 83	struct lsdc_i2c * const li2c = (struct lsdc_i2c *)i2c;
 84	/* set state on the li2c->scl pin */
 85	return __lsdc_gpio_i2c_set(li2c, li2c->scl, state);
 86}
 87
 88static int lsdc_gpio_i2c_get_sda(void *i2c)
 89{
 90	struct lsdc_i2c * const li2c = (struct lsdc_i2c *)i2c;
 91	/* read value from the li2c->sda pin */
 92	return __lsdc_gpio_i2c_get(li2c, li2c->sda);
 93}
 94
 95static int lsdc_gpio_i2c_get_scl(void *i2c)
 96{
 97	struct lsdc_i2c * const li2c = (struct lsdc_i2c *)i2c;
 98	/* read the value from the li2c->scl pin */
 99	return __lsdc_gpio_i2c_get(li2c, li2c->scl);
100}
101
102static void lsdc_destroy_i2c(struct drm_device *ddev, void *data)
103{
104	struct lsdc_i2c *li2c = (struct lsdc_i2c *)data;
105
106	if (li2c) {
107		i2c_del_adapter(&li2c->adapter);
108		kfree(li2c);
109	}
110}
111
112/*
113 * The DC in ls7a1000/ls7a2000/ls2k2000 has builtin gpio hardware
114 *
115 * @reg_base: gpio reg base
116 * @index: output channel index, 0 for PIPE0, 1 for PIPE1
117 */
118int lsdc_create_i2c_chan(struct drm_device *ddev,
119			 struct lsdc_display_pipe *dispipe,
120			 unsigned int index)
121{
122	struct lsdc_device *ldev = to_lsdc(ddev);
123	struct i2c_adapter *adapter;
124	struct lsdc_i2c *li2c;
125	int ret;
126
127	li2c = kzalloc(sizeof(*li2c), GFP_KERNEL);
128	if (!li2c)
129		return -ENOMEM;
130
131	dispipe->li2c = li2c;
132
133	if (index == 0) {
134		li2c->sda = 0x01;  /* pin 0 */
135		li2c->scl = 0x02;  /* pin 1 */
136	} else if (index == 1) {
137		li2c->sda = 0x04;  /* pin 2 */
138		li2c->scl = 0x08;  /* pin 3 */
139	} else {
140		return -ENOENT;
141	}
142
143	li2c->ddev = ddev;
144	li2c->dir_reg = ldev->reg_base + LS7A_DC_GPIO_DIR_REG;
145	li2c->dat_reg = ldev->reg_base + LS7A_DC_GPIO_DAT_REG;
146
147	li2c->bit.setsda = lsdc_gpio_i2c_set_sda;
148	li2c->bit.setscl = lsdc_gpio_i2c_set_scl;
149	li2c->bit.getsda = lsdc_gpio_i2c_get_sda;
150	li2c->bit.getscl = lsdc_gpio_i2c_get_scl;
151	li2c->bit.udelay = 5;
152	li2c->bit.timeout = usecs_to_jiffies(2200);
153	li2c->bit.data = li2c;
154
155	adapter = &li2c->adapter;
156	adapter->algo_data = &li2c->bit;
157	adapter->owner = THIS_MODULE;
158	adapter->dev.parent = ddev->dev;
159	adapter->nr = -1;
160
161	snprintf(adapter->name, sizeof(adapter->name), "lsdc-i2c%u", index);
162
163	i2c_set_adapdata(adapter, li2c);
164
165	ret = i2c_bit_add_bus(adapter);
166	if (ret) {
167		kfree(li2c);
168		return ret;
169	}
170
171	ret = drmm_add_action_or_reset(ddev, lsdc_destroy_i2c, li2c);
172	if (ret)
173		return ret;
174
175	drm_info(ddev, "%s(sda pin mask=%u, scl pin mask=%u) created\n",
176		 adapter->name, li2c->sda, li2c->scl);
177
178	return 0;
179}