1 // SPDX-License-Identifier: GPL-2.0-only
3  * A FSI master controller, using a simple GPIO bit-banging interface
9 #include <linux/fsi.h>
18 #include "fsi-master.h"
24 	struct fsi_master	master;  member
30 	struct gpio_desc	*gpio_enable;	/* FSI enable */
42 #define to_fsi_master_gpio(m) container_of(m, struct fsi_master_gpio, master)
49 static void clock_toggle(struct fsi_master_gpio *master, int count)  in clock_toggle()  argument
54 		if (!master->no_delays)  in clock_toggle()
56 		gpiod_set_value(master->gpio_clk, 0);  in clock_toggle()
57 		if (!master->no_delays)  in clock_toggle()
59 		gpiod_set_value(master->gpio_clk, 1);  in clock_toggle()
63 static int sda_clock_in(struct fsi_master_gpio *master)  in sda_clock_in()  argument
67 	if (!master->no_delays)  in sda_clock_in()
69 	gpiod_set_value(master->gpio_clk, 0);  in sda_clock_in()
72 	gpiod_get_value(master->gpio_data);  in sda_clock_in()
75 	in = gpiod_get_value(master->gpio_data);  in sda_clock_in()
76 	if (!master->no_delays)  in sda_clock_in()
78 	gpiod_set_value(master->gpio_clk, 1);  in sda_clock_in()
82 static void sda_out(struct fsi_master_gpio *master, int value)  in sda_out()  argument
84 	gpiod_set_value(master->gpio_data, value);  in sda_out()
87 static void set_sda_input(struct fsi_master_gpio *master)  in set_sda_input()  argument
89 	gpiod_direction_input(master->gpio_data);  in set_sda_input()
90 	gpiod_set_value(master->gpio_trans, 0);  in set_sda_input()
93 static void set_sda_output(struct fsi_master_gpio *master, int value)  in set_sda_output()  argument
95 	gpiod_set_value(master->gpio_trans, 1);  in set_sda_output()
96 	gpiod_direction_output(master->gpio_data, value);  in set_sda_output()
99 static void clock_zeros(struct fsi_master_gpio *master, int count)  in clock_zeros()  argument
101 	trace_fsi_master_gpio_clock_zeros(master, count);  in clock_zeros()
102 	set_sda_output(master, 1);  in clock_zeros()
103 	clock_toggle(master, count);  in clock_zeros()
106 static void echo_delay(struct fsi_master_gpio *master)  in echo_delay()  argument
108 	clock_zeros(master, master->t_echo_delay);  in echo_delay()
112 static void serial_in(struct fsi_master_gpio *master, struct fsi_gpio_msg *msg,  in serial_in()  argument
117 	set_sda_input(master);  in serial_in()
120 		in_bit = sda_clock_in(master);  in serial_in()
121 		msg->msg <<= 1;  in serial_in()
122 		msg->msg |= ~in_bit & 0x1;	/* Data is active low */  in serial_in()
124 	msg->bits += num_bits;  in serial_in()
126 	trace_fsi_master_gpio_in(master, num_bits, msg->msg);  in serial_in()
129 static void serial_out(struct fsi_master_gpio *master,  in serial_out()  argument
133 	uint64_t msg = ~cmd->msg;	/* Data is active low */  in serial_out()
134 	uint64_t sda_mask = 0x1ULL << (cmd->bits - 1);  in serial_out()
138 	trace_fsi_master_gpio_out(master, cmd->bits, cmd->msg);  in serial_out()
140 	if (!cmd->bits) {  in serial_out()
141 		dev_warn(master->dev, "trying to output 0 bits\n");  in serial_out()
144 	set_sda_output(master, 0);  in serial_out()
147 	sda_out(master, 0);  in serial_out()
148 	clock_toggle(master, 1);  in serial_out()
151 	for (bit = 0; bit < cmd->bits; bit++) {  in serial_out()
152 		next_bit = (msg & sda_mask) >> (cmd->bits - 1);  in serial_out()
154 			sda_out(master, next_bit);  in serial_out()
157 		clock_toggle(master, 1);  in serial_out()
164 	msg->msg <<= bits;  in msg_push_bits()
165 	msg->msg |= data & ((1ull << bits) - 1);  in msg_push_bits()
166 	msg->bits += bits;  in msg_push_bits()
174 	top = msg->bits & 0x3;  in msg_push_crc()
176 	/* start bit, and any non-aligned top bits */  in msg_push_crc()
177 	crc = crc4(0, 1 << top | msg->msg >> (msg->bits - top), top + 1);  in msg_push_crc()
180 	crc = crc4(crc, msg->msg, msg->bits - top);  in msg_push_crc()
185 static bool check_same_address(struct fsi_master_gpio *master, int id,  in check_same_address()  argument
189 	return master->last_addr == (((id & 0x3) << 21) | (addr & ~0x3));  in check_same_address()
192 static bool check_relative_address(struct fsi_master_gpio *master, int id,  in check_relative_address()  argument
195 	uint32_t last_addr = master->last_addr;  in check_relative_address()
201 	/* We may be in 23-bit addressing mode, which uses the id as the  in check_relative_address()
208 	/* remove the top two bits from any 23-bit addressing */  in check_relative_address()
209 	last_addr &= (1 << 21) - 1;  in check_relative_address()
213 	rel_addr = addr - last_addr;  in check_relative_address()
214 	if (rel_addr > 255 || rel_addr < -256)  in check_relative_address()
222 static void last_address_update(struct fsi_master_gpio *master,  in last_address_update()  argument
226 		master->last_addr = LAST_ADDR_INVALID;  in last_address_update()
228 		master->last_addr = ((id & 0x3) << 21) | (addr & ~0x3);  in last_address_update()
234 static void build_ar_command(struct fsi_master_gpio *master,  in build_ar_command()  argument
243 	cmd->bits = 0;  in build_ar_command()
244 	cmd->msg = 0;  in build_ar_command()
247 	addr &= ((1 << 21) - 1);  in build_ar_command()
249 	/* cmd opcodes are variable length - SAME_AR is only two bits */  in build_ar_command()
252 	if (check_same_address(master, id, addr)) {  in build_ar_command()
257 		trace_fsi_master_gpio_cmd_same_addr(master);  in build_ar_command()
259 	} else if (check_relative_address(master, id, addr, &rel_addr)) {  in build_ar_command()
264 		trace_fsi_master_gpio_cmd_rel_addr(master, rel_addr);  in build_ar_command()
269 		trace_fsi_master_gpio_cmd_abs_addr(master, addr);  in build_ar_command()
274 	 * (as it must be naturally-aligned), and the following ds bit.  in build_ar_command()
283 	addr &= ~(size - 1);  in build_ar_command()
300 	cmd->bits = 0;  in build_dpoll_command()
301 	cmd->msg = 0;  in build_dpoll_command()
310 	cmd->bits = 0;  in build_epoll_command()
311 	cmd->msg = 0;  in build_epoll_command()
320 	cmd->bits = 0;  in build_term_command()
321 	cmd->msg = 0;  in build_term_command()
329  * Note: callers rely specifically on this returning -EAGAIN for
334 static int read_one_response(struct fsi_master_gpio *master,  in read_one_response()  argument
349 		serial_in(master, &msg, 1);  in read_one_response()
354 		dev_dbg(master->dev,  in read_one_response()
355 			"Master time out waiting for response\n");  in read_one_response()
357 		return -ETIMEDOUT;  in read_one_response()
364 	serial_in(master, &msg, 4);  in read_one_response()
370 		serial_in(master, &msg, data_size * 8);  in read_one_response()
373 	serial_in(master, &msg, FSI_CRC_SIZE);  in read_one_response()
382 		if (((~msg.msg) & ((1ull << msg.bits) - 1)) == 0)  in read_one_response()
383 			return -ENODEV;  in read_one_response()
384 		dev_dbg(master->dev, "ERR response CRC msg: 0x%016llx (%d bits)\n",  in read_one_response()
386 		return -EAGAIN;  in read_one_response()
397 static int issue_term(struct fsi_master_gpio *master, uint8_t slave)  in issue_term()  argument
407 	serial_out(master, &cmd);  in issue_term()
408 	echo_delay(master);  in issue_term()
411 	rc = read_one_response(master, 0, NULL, &tag);  in issue_term()
413 		dev_err(master->dev,  in issue_term()
415 		return -EIO;  in issue_term()
417 		dev_err(master->dev, "TERM failed; response %d\n", tag);  in issue_term()
418 		return -EIO;  in issue_term()
424 static int poll_for_response(struct fsi_master_gpio *master,  in poll_for_response()  argument
434 	rc = read_one_response(master, size, &response, &tag);  in poll_for_response()
437 	if (rc == -EAGAIN) {  in poll_for_response()
441 			 * Pass it up as a -EIO otherwise upper level will retry  in poll_for_response()
444 			rc = -EIO;  in poll_for_response()
447 		dev_dbg(master->dev,  in poll_for_response()
449 		trace_fsi_master_gpio_crc_rsp_error(master);  in poll_for_response()
452 		clock_zeros(master, FSI_MASTER_EPOLL_CLOCKS);  in poll_for_response()
453 		serial_out(master, &cmd);  in poll_for_response()
454 		echo_delay(master);  in poll_for_response()
466 			val &= (1ull << (size * 8)) - 1;  in poll_for_response()
469 				data_byte[size-i-1] = val;  in poll_for_response()
477 		 * d-poll, not indicated in the hardware protocol  in poll_for_response()
483 			clock_zeros(master, FSI_MASTER_DPOLL_CLOCKS);  in poll_for_response()
484 			serial_out(master, &cmd);  in poll_for_response()
485 			echo_delay(master);  in poll_for_response()
489 		dev_warn(master->dev,  in poll_for_response()
492 		clock_zeros(master, FSI_MASTER_DPOLL_CLOCKS);  in poll_for_response()
494 		issue_term(master, slave);  in poll_for_response()
495 		rc = -EIO;  in poll_for_response()
499 		dev_dbg(master->dev, "ERRA received: 0x%x\n", (int)response.msg);  in poll_for_response()
500 		rc = -EIO;  in poll_for_response()
503 		dev_dbg(master->dev, "ERRC received: 0x%x\n", (int)response.msg);  in poll_for_response()
504 		trace_fsi_master_gpio_crc_cmd_error(master);  in poll_for_response()
505 		rc = -EAGAIN;  in poll_for_response()
510 		trace_fsi_master_gpio_poll_response_busy(master, busy_count);  in poll_for_response()
517 	clock_zeros(master, master->t_send_delay);  in poll_for_response()
523 static int send_request(struct fsi_master_gpio *master,  in send_request()  argument
528 	if (master->external_mode)  in send_request()
529 		return -EBUSY;  in send_request()
532 	serial_out(master, cmd);  in send_request()
533 	echo_delay(master);  in send_request()
539 static int fsi_master_gpio_xfer(struct fsi_master_gpio *master, uint8_t slave,  in fsi_master_gpio_xfer()  argument
542 	int rc = -EAGAIN, retries = 0;  in fsi_master_gpio_xfer()
545 		rc = send_request(master, cmd);  in fsi_master_gpio_xfer()
548 		rc = poll_for_response(master, slave, resp_len, resp);  in fsi_master_gpio_xfer()
549 		if (rc != -EAGAIN)  in fsi_master_gpio_xfer()
551 		rc = -EIO;  in fsi_master_gpio_xfer()
552 		dev_warn(master->dev, "ECRC retry %d\n", retries);  in fsi_master_gpio_xfer()
564 	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);  in fsi_master_gpio_read()  local
569 		return -ENODEV;  in fsi_master_gpio_read()
571 	mutex_lock(&master->cmd_lock);  in fsi_master_gpio_read()
572 	build_ar_command(master, &cmd, id, addr, size, NULL);  in fsi_master_gpio_read()
573 	rc = fsi_master_gpio_xfer(master, id, &cmd, size, val);  in fsi_master_gpio_read()
574 	last_address_update(master, id, rc == 0, addr);  in fsi_master_gpio_read()
575 	mutex_unlock(&master->cmd_lock);  in fsi_master_gpio_read()
583 	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);  in fsi_master_gpio_write()  local
588 		return -ENODEV;  in fsi_master_gpio_write()
590 	mutex_lock(&master->cmd_lock);  in fsi_master_gpio_write()
591 	build_ar_command(master, &cmd, id, addr, size, val);  in fsi_master_gpio_write()
592 	rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);  in fsi_master_gpio_write()
593 	last_address_update(master, id, rc == 0, addr);  in fsi_master_gpio_write()
594 	mutex_unlock(&master->cmd_lock);  in fsi_master_gpio_write()
602 	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);  in fsi_master_gpio_term()  local
607 		return -ENODEV;  in fsi_master_gpio_term()
609 	mutex_lock(&master->cmd_lock);  in fsi_master_gpio_term()
611 	rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);  in fsi_master_gpio_term()
612 	last_address_update(master, id, false, 0);  in fsi_master_gpio_term()
613 	mutex_unlock(&master->cmd_lock);  in fsi_master_gpio_term()
620 	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);  in fsi_master_gpio_break()  local
624 		return -ENODEV;  in fsi_master_gpio_break()
626 	trace_fsi_master_gpio_break(master);  in fsi_master_gpio_break()
628 	mutex_lock(&master->cmd_lock);  in fsi_master_gpio_break()
629 	if (master->external_mode) {  in fsi_master_gpio_break()
630 		mutex_unlock(&master->cmd_lock);  in fsi_master_gpio_break()
631 		return -EBUSY;  in fsi_master_gpio_break()
636 	set_sda_output(master, 1);  in fsi_master_gpio_break()
637 	sda_out(master, 1);  in fsi_master_gpio_break()
638 	clock_toggle(master, FSI_PRE_BREAK_CLOCKS);  in fsi_master_gpio_break()
639 	sda_out(master, 0);  in fsi_master_gpio_break()
640 	clock_toggle(master, FSI_BREAK_CLOCKS);  in fsi_master_gpio_break()
641 	echo_delay(master);  in fsi_master_gpio_break()
642 	sda_out(master, 1);  in fsi_master_gpio_break()
643 	clock_toggle(master, FSI_POST_BREAK_CLOCKS);  in fsi_master_gpio_break()
647 	last_address_update(master, 0, false, 0);  in fsi_master_gpio_break()
648 	mutex_unlock(&master->cmd_lock);  in fsi_master_gpio_break()
656 static void fsi_master_gpio_init(struct fsi_master_gpio *master)  in fsi_master_gpio_init()  argument
660 	gpiod_direction_output(master->gpio_mux, 1);  in fsi_master_gpio_init()
661 	gpiod_direction_output(master->gpio_trans, 1);  in fsi_master_gpio_init()
662 	gpiod_direction_output(master->gpio_enable, 1);  in fsi_master_gpio_init()
663 	gpiod_direction_output(master->gpio_clk, 1);  in fsi_master_gpio_init()
664 	gpiod_direction_output(master->gpio_data, 1);  in fsi_master_gpio_init()
668 	clock_zeros(master, FSI_INIT_CLOCKS);  in fsi_master_gpio_init()
672 static void fsi_master_gpio_init_external(struct fsi_master_gpio *master)  in fsi_master_gpio_init_external()  argument
674 	gpiod_direction_output(master->gpio_mux, 0);  in fsi_master_gpio_init_external()
675 	gpiod_direction_output(master->gpio_trans, 0);  in fsi_master_gpio_init_external()
676 	gpiod_direction_output(master->gpio_enable, 1);  in fsi_master_gpio_init_external()
677 	gpiod_direction_input(master->gpio_clk);  in fsi_master_gpio_init_external()
678 	gpiod_direction_input(master->gpio_data);  in fsi_master_gpio_init_external()
684 	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);  in fsi_master_gpio_link_enable()  local
685 	int rc = -EBUSY;  in fsi_master_gpio_link_enable()
688 		return -ENODEV;  in fsi_master_gpio_link_enable()
690 	mutex_lock(&master->cmd_lock);  in fsi_master_gpio_link_enable()
691 	if (!master->external_mode) {  in fsi_master_gpio_link_enable()
692 		gpiod_set_value(master->gpio_enable, enable ? 1 : 0);  in fsi_master_gpio_link_enable()
695 	mutex_unlock(&master->cmd_lock);  in fsi_master_gpio_link_enable()
703 	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);  in fsi_master_gpio_link_config()  local
706 		return -ENODEV;  in fsi_master_gpio_link_config()
708 	mutex_lock(&master->cmd_lock);  in fsi_master_gpio_link_config()
709 	master->t_send_delay = t_send_delay;  in fsi_master_gpio_link_config()
710 	master->t_echo_delay = t_echo_delay;  in fsi_master_gpio_link_config()
711 	mutex_unlock(&master->cmd_lock);  in fsi_master_gpio_link_config()
719 	struct fsi_master_gpio *master = dev_get_drvdata(dev);  in external_mode_show()  local
721 	return snprintf(buf, PAGE_SIZE - 1, "%u\n",  in external_mode_show()
722 			master->external_mode ? 1 : 0);  in external_mode_show()
728 	struct fsi_master_gpio *master = dev_get_drvdata(dev);  in external_mode_store()  local
739 	mutex_lock(&master->cmd_lock);  in external_mode_store()
741 	if (external_mode == master->external_mode) {  in external_mode_store()
742 		mutex_unlock(&master->cmd_lock);  in external_mode_store()
746 	master->external_mode = external_mode;  in external_mode_store()
747 	if (master->external_mode)  in external_mode_store()
748 		fsi_master_gpio_init_external(master);  in external_mode_store()
750 		fsi_master_gpio_init(master);  in external_mode_store()
752 	mutex_unlock(&master->cmd_lock);  in external_mode_store()
754 	fsi_master_rescan(&master->master);  in external_mode_store()
764 	struct fsi_master_gpio *master = to_fsi_master_gpio(to_fsi_master(dev));  in fsi_master_gpio_release()  local
766 	of_node_put(dev_of_node(master->dev));  in fsi_master_gpio_release()
768 	kfree(master);  in fsi_master_gpio_release()
773 	struct fsi_master_gpio *master;  in fsi_master_gpio_probe()  local
777 	master = kzalloc(sizeof(*master), GFP_KERNEL);  in fsi_master_gpio_probe()
778 	if (!master)  in fsi_master_gpio_probe()
779 		return -ENOMEM;  in fsi_master_gpio_probe()
781 	master->dev = &pdev->dev;  in fsi_master_gpio_probe()
782 	master->master.dev.parent = master->dev;  in fsi_master_gpio_probe()
783 	master->master.dev.of_node = of_node_get(dev_of_node(master->dev));  in fsi_master_gpio_probe()
784 	master->master.dev.release = fsi_master_gpio_release;  in fsi_master_gpio_probe()
785 	master->last_addr = LAST_ADDR_INVALID;  in fsi_master_gpio_probe()
787 	gpio = devm_gpiod_get(&pdev->dev, "clock", 0);  in fsi_master_gpio_probe()
789 		dev_err(&pdev->dev, "failed to get clock gpio\n");  in fsi_master_gpio_probe()
793 	master->gpio_clk = gpio;  in fsi_master_gpio_probe()
795 	gpio = devm_gpiod_get(&pdev->dev, "data", 0);  in fsi_master_gpio_probe()
797 		dev_err(&pdev->dev, "failed to get data gpio\n");  in fsi_master_gpio_probe()
801 	master->gpio_data = gpio;  in fsi_master_gpio_probe()
804 	gpio = devm_gpiod_get_optional(&pdev->dev, "trans", 0);  in fsi_master_gpio_probe()
806 		dev_err(&pdev->dev, "failed to get trans gpio\n");  in fsi_master_gpio_probe()
810 	master->gpio_trans = gpio;  in fsi_master_gpio_probe()
812 	gpio = devm_gpiod_get_optional(&pdev->dev, "enable", 0);  in fsi_master_gpio_probe()
814 		dev_err(&pdev->dev, "failed to get enable gpio\n");  in fsi_master_gpio_probe()
818 	master->gpio_enable = gpio;  in fsi_master_gpio_probe()
820 	gpio = devm_gpiod_get_optional(&pdev->dev, "mux", 0);  in fsi_master_gpio_probe()
822 		dev_err(&pdev->dev, "failed to get mux gpio\n");  in fsi_master_gpio_probe()
826 	master->gpio_mux = gpio;  in fsi_master_gpio_probe()
833 	master->no_delays = device_property_present(&pdev->dev, "no-gpio-delays");  in fsi_master_gpio_probe()
835 	/* Default FSI command delays */  in fsi_master_gpio_probe()
836 	master->t_send_delay = FSI_SEND_DELAY_CLOCKS;  in fsi_master_gpio_probe()
837 	master->t_echo_delay = FSI_ECHO_DELAY_CLOCKS;  in fsi_master_gpio_probe()
839 	master->master.n_links = 1;  in fsi_master_gpio_probe()
840 	master->master.flags = FSI_MASTER_FLAG_SWCLOCK;  in fsi_master_gpio_probe()
841 	master->master.read = fsi_master_gpio_read;  in fsi_master_gpio_probe()
842 	master->master.write = fsi_master_gpio_write;  in fsi_master_gpio_probe()
843 	master->master.term = fsi_master_gpio_term;  in fsi_master_gpio_probe()
844 	master->master.send_break = fsi_master_gpio_break;  in fsi_master_gpio_probe()
845 	master->master.link_enable = fsi_master_gpio_link_enable;  in fsi_master_gpio_probe()
846 	master->master.link_config = fsi_master_gpio_link_config;  in fsi_master_gpio_probe()
847 	platform_set_drvdata(pdev, master);  in fsi_master_gpio_probe()
848 	mutex_init(&master->cmd_lock);  in fsi_master_gpio_probe()
850 	fsi_master_gpio_init(master);  in fsi_master_gpio_probe()
852 	rc = device_create_file(&pdev->dev, &dev_attr_external_mode);  in fsi_master_gpio_probe()
856 	rc = fsi_master_register(&master->master);  in fsi_master_gpio_probe()
858 		device_remove_file(&pdev->dev, &dev_attr_external_mode);  in fsi_master_gpio_probe()
859 		put_device(&master->master.dev);  in fsi_master_gpio_probe()
864 	kfree(master);  in fsi_master_gpio_probe()
872 	struct fsi_master_gpio *master = platform_get_drvdata(pdev);  in fsi_master_gpio_remove()  local
874 	device_remove_file(&pdev->dev, &dev_attr_external_mode);  in fsi_master_gpio_remove()
876 	fsi_master_unregister(&master->master);  in fsi_master_gpio_remove()
880 	{ .compatible = "fsi-master-gpio" },
887 		.name		= "fsi-master-gpio",
895 MODULE_DESCRIPTION("A FSI master controller, using a simple GPIO bit-banging interface");