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2024-01-04 1543e317f1da31b75942316931e8f491a8920811 
 kernel/drivers/tty/serial/8250/8250_bcm2835aux.c
....@@ -6,6 +6,10 @@
66  *
77  * Based on 8250_lpc18xx.c:
88  * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
9
+ *
10
+ * The bcm2835aux is capable of RTS auto flow-control, but this driver doesn't
11
+ * take advantage of it yet.  When adding support, be sure not to enable it
12
+ * simultaneously to rs485.
913  */
1014 
1115 #include <linux/clk.h>
....@@ -16,14 +20,67 @@
1620 
1721 #include "8250.h"
1822 
23
+#define BCM2835_AUX_UART_CNTL		8
24
+#define BCM2835_AUX_UART_CNTL_RXEN	0x01 /* Receiver enable */
25
+#define BCM2835_AUX_UART_CNTL_TXEN	0x02 /* Transmitter enable */
26
+#define BCM2835_AUX_UART_CNTL_AUTORTS	0x04 /* RTS set by RX fill level */
27
+#define BCM2835_AUX_UART_CNTL_AUTOCTS	0x08 /* CTS stops transmitter */
28
+#define BCM2835_AUX_UART_CNTL_RTS3	0x00 /* RTS set until 3 chars left */
29
+#define BCM2835_AUX_UART_CNTL_RTS2	0x10 /* RTS set until 2 chars left */
30
+#define BCM2835_AUX_UART_CNTL_RTS1	0x20 /* RTS set until 1 chars left */
31
+#define BCM2835_AUX_UART_CNTL_RTS4	0x30 /* RTS set until 4 chars left */
32
+#define BCM2835_AUX_UART_CNTL_RTSINV	0x40 /* Invert auto RTS polarity */
33
+#define BCM2835_AUX_UART_CNTL_CTSINV	0x80 /* Invert auto CTS polarity */
34
+
35
+/**
36
+ * struct bcm2835aux_data - driver private data of BCM2835 auxiliary UART
37
+ * @clk: clock producer of the port's uartclk
38
+ * @line: index of the port's serial8250_ports[] entry
39
+ * @cntl: cached copy of CNTL register
40
+ */
1941 struct bcm2835aux_data {
20
-	struct uart_8250_port uart;
2142 	struct clk *clk;
2243 	int line;
44
+	u32 cntl;
2345 };
46
+
47
+static void bcm2835aux_rs485_start_tx(struct uart_8250_port *up)
48
+{
49
+	if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
50
+		struct bcm2835aux_data *data = dev_get_drvdata(up->port.dev);
51
+
52
+		data->cntl &= ~BCM2835_AUX_UART_CNTL_RXEN;
53
+		serial_out(up, BCM2835_AUX_UART_CNTL, data->cntl);
54
+	}
55
+
56
+	/*
57
+	 * On the bcm2835aux, the MCR register contains no other
58
+	 * flags besides RTS.  So no need for a read-modify-write.
59
+	 */
60
+	if (up->port.rs485.flags & SER_RS485_RTS_ON_SEND)
61
+		serial8250_out_MCR(up, 0);
62
+	else
63
+		serial8250_out_MCR(up, UART_MCR_RTS);
64
+}
65
+
66
+static void bcm2835aux_rs485_stop_tx(struct uart_8250_port *up)
67
+{
68
+	if (up->port.rs485.flags & SER_RS485_RTS_AFTER_SEND)
69
+		serial8250_out_MCR(up, 0);
70
+	else
71
+		serial8250_out_MCR(up, UART_MCR_RTS);
72
+
73
+	if (!(up->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
74
+		struct bcm2835aux_data *data = dev_get_drvdata(up->port.dev);
75
+
76
+		data->cntl |= BCM2835_AUX_UART_CNTL_RXEN;
77
+		serial_out(up, BCM2835_AUX_UART_CNTL, data->cntl);
78
+	}
79
+}
2480 
2581 static int bcm2835aux_serial_probe(struct platform_device *pdev)
2682 {
83
+	struct uart_8250_port up = { };
2784 	struct bcm2835aux_data *data;
2885 	struct resource *res;
2986 	int ret;
....@@ -34,33 +91,33 @@
3491 		return -ENOMEM;
3592 
3693 	/* initialize data */
37
-	spin_lock_init(&data->uart.port.lock);
38
-	data->uart.capabilities = UART_CAP_FIFO | UART_CAP_MINI;
39
-	data->uart.port.dev = &pdev->dev;
40
-	data->uart.port.regshift = 2;
41
-	data->uart.port.type = PORT_16550;
42
-	data->uart.port.iotype = UPIO_MEM;
43
-	data->uart.port.fifosize = 8;
44
-	data->uart.port.flags = UPF_SHARE_IRQ |
45
-				UPF_FIXED_PORT |
46
-				UPF_FIXED_TYPE |
47
-				UPF_SKIP_TEST;
94
+	up.capabilities = UART_CAP_FIFO | UART_CAP_MINI;
95
+	up.port.dev = &pdev->dev;
96
+	up.port.regshift = 2;
97
+	up.port.type = PORT_16550;
98
+	up.port.iotype = UPIO_MEM;
99
+	up.port.fifosize = 8;
100
+	up.port.flags = UPF_SHARE_IRQ | UPF_FIXED_PORT | UPF_FIXED_TYPE |
101
+			UPF_SKIP_TEST | UPF_IOREMAP;
102
+	up.port.rs485_config = serial8250_em485_config;
103
+	up.rs485_start_tx = bcm2835aux_rs485_start_tx;
104
+	up.rs485_stop_tx = bcm2835aux_rs485_stop_tx;
105
+
106
+	/* initialize cached copy with power-on reset value */
107
+	data->cntl = BCM2835_AUX_UART_CNTL_RXEN | BCM2835_AUX_UART_CNTL_TXEN;
108
+
109
+	platform_set_drvdata(pdev, data);
48110 
49111 	/* get the clock - this also enables the HW */
50112 	data->clk = devm_clk_get(&pdev->dev, NULL);
51
-	ret = PTR_ERR_OR_ZERO(data->clk);
52
-	if (ret) {
53
-		dev_err(&pdev->dev, "could not get clk: %d\n", ret);
54
-		return ret;
55
-	}
113
+	if (IS_ERR(data->clk))
114
+		return dev_err_probe(&pdev->dev, PTR_ERR(data->clk), "could not get clk\n");
56115 
57116 	/* get the interrupt */
58117 	ret = platform_get_irq(pdev, 0);
59
-	if (ret < 0) {
60
-		dev_err(&pdev->dev, "irq not found - %i", ret);
118
+	if (ret < 0)
61119 		return ret;
62
-	}
63
-	data->uart.port.irq = ret;
120
+	up.port.irq = ret;
64121 
65122 	/* map the main registers */
66123 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
....@@ -68,15 +125,13 @@
68125 		dev_err(&pdev->dev, "memory resource not found");
69126 		return -EINVAL;
70127 	}
71
-	data->uart.port.membase = devm_ioremap_resource(&pdev->dev, res);
72
-	ret = PTR_ERR_OR_ZERO(data->uart.port.membase);
73
-	if (ret)
74
-		return ret;
128
+	up.port.mapbase = res->start;
129
+	up.port.mapsize = resource_size(res);
75130 
76131 	/* Check for a fixed line number */
77132 	ret = of_alias_get_id(pdev->dev.of_node, "serial");
78133 	if (ret >= 0)
79
-		data->uart.port.line = ret;
134
+		up.port.line = ret;
80135 
81136 	/* enable the clock as a last step */
82137 	ret = clk_prepare_enable(data->clk);
....@@ -91,18 +146,15 @@
91146 	 * so we have to multiply the actual clock by 2
92147 	 * to get identical baudrates.
93148 	 */
94
-	data->uart.port.uartclk = clk_get_rate(data->clk) * 2;
149
+	up.port.uartclk = clk_get_rate(data->clk) * 2;
95150 
96151 	/* register the port */
97
-	ret = serial8250_register_8250_port(&data->uart);
152
+	ret = serial8250_register_8250_port(&up);
98153 	if (ret < 0) {
99
-		dev_err(&pdev->dev, "unable to register 8250 port - %d\n",
100
-			ret);
154
+		dev_err_probe(&pdev->dev, ret, "unable to register 8250 port\n");
101155 		goto dis_clk;
102156 	}
103157 	data->line = ret;
104
-
105
-	platform_set_drvdata(pdev, data);
106158 
107159 	return 0;
108160 
....@@ -137,6 +189,24 @@
137189 };
138190 module_platform_driver(bcm2835aux_serial_driver);
139191 
192
+#ifdef CONFIG_SERIAL_8250_CONSOLE
193
+
194
+static int __init early_bcm2835aux_setup(struct earlycon_device *device,
195
+					const char *options)
196
+{
197
+	if (!device->port.membase)
198
+		return -ENODEV;
199
+
200
+	device->port.iotype = UPIO_MEM32;
201
+	device->port.regshift = 2;
202
+
203
+	return early_serial8250_setup(device, NULL);
204
+}
205
+
206
+OF_EARLYCON_DECLARE(bcm2835aux, "brcm,bcm2835-aux-uart",
207
+		    early_bcm2835aux_setup);
208
+#endif
209
+
140210 MODULE_DESCRIPTION("BCM2835 auxiliar UART driver");
141211 MODULE_AUTHOR("Martin Sperl <kernel@martin.sperl.org>");
142212 MODULE_LICENSE("GPL v2");