1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 * Helpers for controlling modem lines via GPIO
  4 *
  5 * Copyright (C) 2014 Paratronic S.A.
  6 */
  7
  8#include <linux/err.h>
  9#include <linux/device.h>
 10#include <linux/irq.h>
 11#include <linux/gpio/consumer.h>
 12#include <linux/termios.h>
 13#include <linux/serial_core.h>
 14#include <linux/module.h>
 15#include <linux/property.h>
 16
 17#include "serial_mctrl_gpio.h"
 18
 19struct mctrl_gpios {
 20	struct uart_port *port;
 21	struct gpio_desc *gpio[UART_GPIO_MAX];
 22	int irq[UART_GPIO_MAX];
 23	unsigned int mctrl_prev;
 24	bool mctrl_on;
 25};
 26
 27static const struct {
 28	const char *name;
 29	unsigned int mctrl;
 30	enum gpiod_flags flags;
 31} mctrl_gpios_desc[UART_GPIO_MAX] = {
 32	{ "cts", TIOCM_CTS, GPIOD_IN, },
 33	{ "dsr", TIOCM_DSR, GPIOD_IN, },
 34	{ "dcd", TIOCM_CD,  GPIOD_IN, },
 35	{ "rng", TIOCM_RNG, GPIOD_IN, },
 36	{ "rts", TIOCM_RTS, GPIOD_OUT_LOW, },
 37	{ "dtr", TIOCM_DTR, GPIOD_OUT_LOW, },
 38};
 39
 40static bool mctrl_gpio_flags_is_dir_out(unsigned int idx)
 41{
 42	return mctrl_gpios_desc[idx].flags & GPIOD_FLAGS_BIT_DIR_OUT;
 43}
 44
 45void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
 46{
 47	enum mctrl_gpio_idx i;
 48	struct gpio_desc *desc_array[UART_GPIO_MAX];
 49	DECLARE_BITMAP(values, UART_GPIO_MAX);
 50	unsigned int count = 0;
 51
 52	if (gpios == NULL)
 53		return;
 54
 55	for (i = 0; i < UART_GPIO_MAX; i++)
 56		if (gpios->gpio[i] && mctrl_gpio_flags_is_dir_out(i)) {
 57			desc_array[count] = gpios->gpio[i];
 58			__assign_bit(count, values,
 59				     mctrl & mctrl_gpios_desc[i].mctrl);
 60			count++;
 61		}
 62	gpiod_set_array_value(count, desc_array, NULL, values);
 63}
 64EXPORT_SYMBOL_GPL(mctrl_gpio_set);
 65
 66struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
 67				      enum mctrl_gpio_idx gidx)
 68{
 69	if (gpios == NULL)
 70		return NULL;
 71
 72	return gpios->gpio[gidx];
 73}
 74EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
 75
 76unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
 77{
 78	enum mctrl_gpio_idx i;
 79
 80	if (gpios == NULL)
 81		return *mctrl;
 82
 83	for (i = 0; i < UART_GPIO_MAX; i++) {
 84		if (gpios->gpio[i] && !mctrl_gpio_flags_is_dir_out(i)) {
 85			if (gpiod_get_value(gpios->gpio[i]))
 86				*mctrl |= mctrl_gpios_desc[i].mctrl;
 87			else
 88				*mctrl &= ~mctrl_gpios_desc[i].mctrl;
 89		}
 90	}
 91
 92	return *mctrl;
 93}
 94EXPORT_SYMBOL_GPL(mctrl_gpio_get);
 95
 96unsigned int
 97mctrl_gpio_get_outputs(struct mctrl_gpios *gpios, unsigned int *mctrl)
 98{
 99	enum mctrl_gpio_idx i;
100
101	if (gpios == NULL)
102		return *mctrl;
103
104	for (i = 0; i < UART_GPIO_MAX; i++) {
105		if (gpios->gpio[i] && mctrl_gpio_flags_is_dir_out(i)) {
106			if (gpiod_get_value(gpios->gpio[i]))
107				*mctrl |= mctrl_gpios_desc[i].mctrl;
108			else
109				*mctrl &= ~mctrl_gpios_desc[i].mctrl;
110		}
111	}
112
113	return *mctrl;
114}
115EXPORT_SYMBOL_GPL(mctrl_gpio_get_outputs);
116
117struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx)
118{
119	struct mctrl_gpios *gpios;
120	enum mctrl_gpio_idx i;
121
122	gpios = devm_kzalloc(dev, sizeof(*gpios), GFP_KERNEL);
123	if (!gpios)
124		return ERR_PTR(-ENOMEM);
125
126	for (i = 0; i < UART_GPIO_MAX; i++) {
127		char *gpio_str;
128		bool present;
129
130		/* Check if GPIO property exists and continue if not */
131		gpio_str = kasprintf(GFP_KERNEL, "%s-gpios",
132				     mctrl_gpios_desc[i].name);
133		if (!gpio_str)
134			continue;
135
136		present = device_property_present(dev, gpio_str);
137		kfree(gpio_str);
138		if (!present)
139			continue;
140
141		gpios->gpio[i] =
142			devm_gpiod_get_index_optional(dev,
143						      mctrl_gpios_desc[i].name,
144						      idx,
145						      mctrl_gpios_desc[i].flags);
146
147		if (IS_ERR(gpios->gpio[i]))
148			return ERR_CAST(gpios->gpio[i]);
149	}
150
151	return gpios;
152}
153EXPORT_SYMBOL_GPL(mctrl_gpio_init_noauto);
154
155#define MCTRL_ANY_DELTA (TIOCM_RI | TIOCM_DSR | TIOCM_CD | TIOCM_CTS)
156static irqreturn_t mctrl_gpio_irq_handle(int irq, void *context)
157{
158	struct mctrl_gpios *gpios = context;
159	struct uart_port *port = gpios->port;
160	u32 mctrl = gpios->mctrl_prev;
161	u32 mctrl_diff;
162	unsigned long flags;
163
164	mctrl_gpio_get(gpios, &mctrl);
165
166	spin_lock_irqsave(&port->lock, flags);
167
168	mctrl_diff = mctrl ^ gpios->mctrl_prev;
169	gpios->mctrl_prev = mctrl;
170
171	if (mctrl_diff & MCTRL_ANY_DELTA && port->state != NULL) {
172		if ((mctrl_diff & mctrl) & TIOCM_RI)
173			port->icount.rng++;
174
175		if ((mctrl_diff & mctrl) & TIOCM_DSR)
176			port->icount.dsr++;
177
178		if (mctrl_diff & TIOCM_CD)
179			uart_handle_dcd_change(port, mctrl & TIOCM_CD);
180
181		if (mctrl_diff & TIOCM_CTS)
182			uart_handle_cts_change(port, mctrl & TIOCM_CTS);
183
184		wake_up_interruptible(&port->state->port.delta_msr_wait);
185	}
186
187	spin_unlock_irqrestore(&port->lock, flags);
188
189	return IRQ_HANDLED;
190}
191
192struct mctrl_gpios *mctrl_gpio_init(struct uart_port *port, unsigned int idx)
193{
194	struct mctrl_gpios *gpios;
195	enum mctrl_gpio_idx i;
196
197	gpios = mctrl_gpio_init_noauto(port->dev, idx);
198	if (IS_ERR(gpios))
199		return gpios;
200
201	gpios->port = port;
202
203	for (i = 0; i < UART_GPIO_MAX; ++i) {
204		int ret;
205
206		if (!gpios->gpio[i] || mctrl_gpio_flags_is_dir_out(i))
207			continue;
208
209		ret = gpiod_to_irq(gpios->gpio[i]);
210		if (ret <= 0) {
211			dev_err(port->dev,
212				"failed to find corresponding irq for %s (idx=%d, err=%d)\n",
213				mctrl_gpios_desc[i].name, idx, ret);
214			return ERR_PTR(ret);
215		}
216		gpios->irq[i] = ret;
217
218		/* irqs should only be enabled in .enable_ms */
219		irq_set_status_flags(gpios->irq[i], IRQ_NOAUTOEN);
220
221		ret = devm_request_irq(port->dev, gpios->irq[i],
222				       mctrl_gpio_irq_handle,
223				       IRQ_TYPE_EDGE_BOTH, dev_name(port->dev),
224				       gpios);
225		if (ret) {
226			/* alternatively implement polling */
227			dev_err(port->dev,
228				"failed to request irq for %s (idx=%d, err=%d)\n",
229				mctrl_gpios_desc[i].name, idx, ret);
230			return ERR_PTR(ret);
231		}
232	}
233
234	return gpios;
235}
236EXPORT_SYMBOL_GPL(mctrl_gpio_init);
237
238void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
239{
240	enum mctrl_gpio_idx i;
241
242	if (gpios == NULL)
243		return;
244
245	for (i = 0; i < UART_GPIO_MAX; i++) {
246		if (gpios->irq[i])
247			devm_free_irq(gpios->port->dev, gpios->irq[i], gpios);
248
249		if (gpios->gpio[i])
250			devm_gpiod_put(dev, gpios->gpio[i]);
251	}
252	devm_kfree(dev, gpios);
253}
254EXPORT_SYMBOL_GPL(mctrl_gpio_free);
255
256void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)
257{
258	enum mctrl_gpio_idx i;
259
260	if (gpios == NULL)
261		return;
262
263	/* .enable_ms may be called multiple times */
264	if (gpios->mctrl_on)
265		return;
266
267	gpios->mctrl_on = true;
268
269	/* get initial status of modem lines GPIOs */
270	mctrl_gpio_get(gpios, &gpios->mctrl_prev);
271
272	for (i = 0; i < UART_GPIO_MAX; ++i) {
273		if (!gpios->irq[i])
274			continue;
275
276		enable_irq(gpios->irq[i]);
277	}
278}
279EXPORT_SYMBOL_GPL(mctrl_gpio_enable_ms);
280
281void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)
282{
283	enum mctrl_gpio_idx i;
284
285	if (gpios == NULL)
286		return;
287
288	if (!gpios->mctrl_on)
289		return;
290
291	gpios->mctrl_on = false;
292
293	for (i = 0; i < UART_GPIO_MAX; ++i) {
294		if (!gpios->irq[i])
295			continue;
296
297		disable_irq(gpios->irq[i]);
298	}
299}
300EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms);
301
302MODULE_LICENSE("GPL");