xref: /openbmc/u-boot/drivers/serial/serial_msm.c (revision ae485b54)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Qualcomm UART driver
4  *
5  * (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
6  *
7  * UART will work in Data Mover mode.
8  * Based on Linux driver.
9  */
10 
11 #include <common.h>
12 #include <clk.h>
13 #include <dm.h>
14 #include <errno.h>
15 #include <serial.h>
16 #include <watchdog.h>
17 #include <asm/io.h>
18 #include <linux/compiler.h>
19 #include <dm/pinctrl.h>
20 
21 /* Serial registers - this driver works in uartdm mode*/
22 
23 #define UARTDM_DMRX             0x34 /* Max RX transfer length */
24 #define UARTDM_NCF_TX           0x40 /* Number of chars to TX */
25 
26 #define UARTDM_RXFS             0x50 /* RX channel status register */
27 #define UARTDM_RXFS_BUF_SHIFT   0x7  /* Number of bytes in the packing buffer */
28 #define UARTDM_RXFS_BUF_MASK    0x7
29 #define UARTDM_MR1				 0x00
30 #define UARTDM_MR2				 0x04
31 #define UARTDM_CSR				 0xA0
32 
33 #define UARTDM_SR                0xA4 /* Status register */
34 #define UARTDM_SR_RX_READY       (1 << 0) /* Word is the receiver FIFO */
35 #define UARTDM_SR_TX_EMPTY       (1 << 3) /* Transmitter underrun */
36 #define UARTDM_SR_UART_OVERRUN   (1 << 4) /* Receive overrun */
37 
38 #define UARTDM_CR                         0xA8 /* Command register */
39 #define UARTDM_CR_CMD_RESET_ERR           (3 << 4) /* Clear overrun error */
40 #define UARTDM_CR_CMD_RESET_STALE_INT     (8 << 4) /* Clears stale irq */
41 #define UARTDM_CR_CMD_RESET_TX_READY      (3 << 8) /* Clears TX Ready irq*/
42 #define UARTDM_CR_CMD_FORCE_STALE         (4 << 8) /* Causes stale event */
43 #define UARTDM_CR_CMD_STALE_EVENT_DISABLE (6 << 8) /* Disable stale event */
44 
45 #define UARTDM_IMR                0xB0 /* Interrupt mask register */
46 #define UARTDM_ISR                0xB4 /* Interrupt status register */
47 #define UARTDM_ISR_TX_READY       0x80 /* TX FIFO empty */
48 
49 #define UARTDM_TF               0x100 /* UART Transmit FIFO register */
50 #define UARTDM_RF               0x140 /* UART Receive FIFO register */
51 
52 #define UART_DM_CLK_RX_TX_BIT_RATE 0xCC
53 #define MSM_BOOT_UART_DM_8_N_1_MODE 0x34
54 #define MSM_BOOT_UART_DM_CMD_RESET_RX 0x10
55 #define MSM_BOOT_UART_DM_CMD_RESET_TX 0x20
56 
57 DECLARE_GLOBAL_DATA_PTR;
58 
59 struct msm_serial_data {
60 	phys_addr_t base;
61 	unsigned chars_cnt; /* number of buffered chars */
62 	uint32_t chars_buf; /* buffered chars */
63 };
64 
65 static int msm_serial_fetch(struct udevice *dev)
66 {
67 	struct msm_serial_data *priv = dev_get_priv(dev);
68 	unsigned sr;
69 
70 	if (priv->chars_cnt)
71 		return priv->chars_cnt;
72 
73 	/* Clear error in case of buffer overrun */
74 	if (readl(priv->base + UARTDM_SR) & UARTDM_SR_UART_OVERRUN)
75 		writel(UARTDM_CR_CMD_RESET_ERR, priv->base + UARTDM_CR);
76 
77 	/* We need to fetch new character */
78 	sr = readl(priv->base + UARTDM_SR);
79 
80 	if (sr & UARTDM_SR_RX_READY) {
81 		/* There are at least 4 bytes in fifo */
82 		priv->chars_buf = readl(priv->base + UARTDM_RF);
83 		priv->chars_cnt = 4;
84 	} else {
85 		/* Check if there is anything in fifo */
86 		priv->chars_cnt = readl(priv->base + UARTDM_RXFS);
87 		/* Extract number of characters in UART packing buffer*/
88 		priv->chars_cnt = (priv->chars_cnt >>
89 				   UARTDM_RXFS_BUF_SHIFT) &
90 				  UARTDM_RXFS_BUF_MASK;
91 		if (!priv->chars_cnt)
92 			return 0;
93 
94 		/* There is at least one charcter, move it to fifo */
95 		writel(UARTDM_CR_CMD_FORCE_STALE,
96 		       priv->base + UARTDM_CR);
97 
98 		priv->chars_buf = readl(priv->base + UARTDM_RF);
99 		writel(UARTDM_CR_CMD_RESET_STALE_INT,
100 		       priv->base + UARTDM_CR);
101 		writel(0x7, priv->base + UARTDM_DMRX);
102 	}
103 
104 	return priv->chars_cnt;
105 }
106 
107 static int msm_serial_getc(struct udevice *dev)
108 {
109 	struct msm_serial_data *priv = dev_get_priv(dev);
110 	char c;
111 
112 	if (!msm_serial_fetch(dev))
113 		return -EAGAIN;
114 
115 	c = priv->chars_buf & 0xFF;
116 	priv->chars_buf >>= 8;
117 	priv->chars_cnt--;
118 
119 	return c;
120 }
121 
122 static int msm_serial_putc(struct udevice *dev, const char ch)
123 {
124 	struct msm_serial_data *priv = dev_get_priv(dev);
125 
126 	if (!(readl(priv->base + UARTDM_SR) & UARTDM_SR_TX_EMPTY) &&
127 	    !(readl(priv->base + UARTDM_ISR) & UARTDM_ISR_TX_READY))
128 		return -EAGAIN;
129 
130 	writel(UARTDM_CR_CMD_RESET_TX_READY, priv->base + UARTDM_CR);
131 
132 	writel(1, priv->base + UARTDM_NCF_TX);
133 	writel(ch, priv->base + UARTDM_TF);
134 
135 	return 0;
136 }
137 
138 static int msm_serial_pending(struct udevice *dev, bool input)
139 {
140 	if (input) {
141 		if (msm_serial_fetch(dev))
142 			return 1;
143 	}
144 
145 	return 0;
146 }
147 
148 static const struct dm_serial_ops msm_serial_ops = {
149 	.putc = msm_serial_putc,
150 	.pending = msm_serial_pending,
151 	.getc = msm_serial_getc,
152 };
153 
154 static int msm_uart_clk_init(struct udevice *dev)
155 {
156 	uint clk_rate = fdtdec_get_uint(gd->fdt_blob, dev_of_offset(dev),
157 					"clock-frequency", 115200);
158 	uint clkd[2]; /* clk_id and clk_no */
159 	int clk_offset;
160 	struct udevice *clk_dev;
161 	struct clk clk;
162 	int ret;
163 
164 	ret = fdtdec_get_int_array(gd->fdt_blob, dev_of_offset(dev), "clock",
165 				   clkd, 2);
166 	if (ret)
167 		return ret;
168 
169 	clk_offset = fdt_node_offset_by_phandle(gd->fdt_blob, clkd[0]);
170 	if (clk_offset < 0)
171 		return clk_offset;
172 
173 	ret = uclass_get_device_by_of_offset(UCLASS_CLK, clk_offset, &clk_dev);
174 	if (ret)
175 		return ret;
176 
177 	clk.id = clkd[1];
178 	ret = clk_request(clk_dev, &clk);
179 	if (ret < 0)
180 		return ret;
181 
182 	ret = clk_set_rate(&clk, clk_rate);
183 	clk_free(&clk);
184 	if (ret < 0)
185 		return ret;
186 
187 	return 0;
188 }
189 
190 static void uart_dm_init(struct msm_serial_data *priv)
191 {
192 	writel(UART_DM_CLK_RX_TX_BIT_RATE, priv->base + UARTDM_CSR);
193 	writel(0x0, priv->base + UARTDM_MR1);
194 	writel(MSM_BOOT_UART_DM_8_N_1_MODE, priv->base + UARTDM_MR2);
195 	writel(MSM_BOOT_UART_DM_CMD_RESET_RX, priv->base + UARTDM_CR);
196 	writel(MSM_BOOT_UART_DM_CMD_RESET_TX, priv->base + UARTDM_CR);
197 }
198 static int msm_serial_probe(struct udevice *dev)
199 {
200 	int ret;
201 	struct msm_serial_data *priv = dev_get_priv(dev);
202 
203 	/* No need to reinitialize the UART after relocation */
204 	if (gd->flags & GD_FLG_RELOC)
205 		return 0;
206 
207 	ret = msm_uart_clk_init(dev);
208 	if (ret)
209 		return ret;
210 
211 	pinctrl_select_state(dev, "uart");
212 	uart_dm_init(priv);
213 
214 	return 0;
215 }
216 
217 static int msm_serial_ofdata_to_platdata(struct udevice *dev)
218 {
219 	struct msm_serial_data *priv = dev_get_priv(dev);
220 
221 	priv->base = devfdt_get_addr(dev);
222 	if (priv->base == FDT_ADDR_T_NONE)
223 		return -EINVAL;
224 
225 	return 0;
226 }
227 
228 static const struct udevice_id msm_serial_ids[] = {
229 	{ .compatible = "qcom,msm-uartdm-v1.4" },
230 	{ }
231 };
232 
233 U_BOOT_DRIVER(serial_msm) = {
234 	.name	= "serial_msm",
235 	.id	= UCLASS_SERIAL,
236 	.of_match = msm_serial_ids,
237 	.ofdata_to_platdata = msm_serial_ofdata_to_platdata,
238 	.priv_auto_alloc_size = sizeof(struct msm_serial_data),
239 	.probe = msm_serial_probe,
240 	.ops	= &msm_serial_ops,
241 };
242