1 /* 2 * Qualcomm UART driver 3 * 4 * (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com> 5 * 6 * UART will work in Data Mover mode. 7 * Based on Linux driver. 8 * 9 * SPDX-License-Identifier: GPL-2.0+ 10 */ 11 12 #include <common.h> 13 #include <clk.h> 14 #include <dm.h> 15 #include <errno.h> 16 #include <serial.h> 17 #include <watchdog.h> 18 #include <asm/io.h> 19 #include <linux/compiler.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 30 #define UARTDM_SR 0xA4 /* Status register */ 31 #define UARTDM_SR_RX_READY (1 << 0) /* Word is the receiver FIFO */ 32 #define UARTDM_SR_TX_EMPTY (1 << 3) /* Transmitter underrun */ 33 #define UARTDM_SR_UART_OVERRUN (1 << 4) /* Receive overrun */ 34 35 #define UARTDM_CR 0xA8 /* Command register */ 36 #define UARTDM_CR_CMD_RESET_ERR (3 << 4) /* Clear overrun error */ 37 #define UARTDM_CR_CMD_RESET_STALE_INT (8 << 4) /* Clears stale irq */ 38 #define UARTDM_CR_CMD_RESET_TX_READY (3 << 8) /* Clears TX Ready irq*/ 39 #define UARTDM_CR_CMD_FORCE_STALE (4 << 8) /* Causes stale event */ 40 #define UARTDM_CR_CMD_STALE_EVENT_DISABLE (6 << 8) /* Disable stale event */ 41 42 #define UARTDM_IMR 0xB0 /* Interrupt mask register */ 43 #define UARTDM_ISR 0xB4 /* Interrupt status register */ 44 #define UARTDM_ISR_TX_READY 0x80 /* TX FIFO empty */ 45 46 #define UARTDM_TF 0x100 /* UART Transmit FIFO register */ 47 #define UARTDM_RF 0x140 /* UART Receive FIFO register */ 48 49 50 DECLARE_GLOBAL_DATA_PTR; 51 52 struct msm_serial_data { 53 phys_addr_t base; 54 unsigned chars_cnt; /* number of buffered chars */ 55 uint32_t chars_buf; /* buffered chars */ 56 }; 57 58 static int msm_serial_fetch(struct udevice *dev) 59 { 60 struct msm_serial_data *priv = dev_get_priv(dev); 61 unsigned sr; 62 63 if (priv->chars_cnt) 64 return priv->chars_cnt; 65 66 /* Clear error in case of buffer overrun */ 67 if (readl(priv->base + UARTDM_SR) & UARTDM_SR_UART_OVERRUN) 68 writel(UARTDM_CR_CMD_RESET_ERR, priv->base + UARTDM_CR); 69 70 /* We need to fetch new character */ 71 sr = readl(priv->base + UARTDM_SR); 72 73 if (sr & UARTDM_SR_RX_READY) { 74 /* There are at least 4 bytes in fifo */ 75 priv->chars_buf = readl(priv->base + UARTDM_RF); 76 priv->chars_cnt = 4; 77 } else { 78 /* Check if there is anything in fifo */ 79 priv->chars_cnt = readl(priv->base + UARTDM_RXFS); 80 /* Extract number of characters in UART packing buffer*/ 81 priv->chars_cnt = (priv->chars_cnt >> 82 UARTDM_RXFS_BUF_SHIFT) & 83 UARTDM_RXFS_BUF_MASK; 84 if (!priv->chars_cnt) 85 return 0; 86 87 /* There is at least one charcter, move it to fifo */ 88 writel(UARTDM_CR_CMD_FORCE_STALE, 89 priv->base + UARTDM_CR); 90 91 priv->chars_buf = readl(priv->base + UARTDM_RF); 92 writel(UARTDM_CR_CMD_RESET_STALE_INT, 93 priv->base + UARTDM_CR); 94 writel(0x7, priv->base + UARTDM_DMRX); 95 } 96 97 return priv->chars_cnt; 98 } 99 100 static int msm_serial_getc(struct udevice *dev) 101 { 102 struct msm_serial_data *priv = dev_get_priv(dev); 103 char c; 104 105 if (!msm_serial_fetch(dev)) 106 return -EAGAIN; 107 108 c = priv->chars_buf & 0xFF; 109 priv->chars_buf >>= 8; 110 priv->chars_cnt--; 111 112 return c; 113 } 114 115 static int msm_serial_putc(struct udevice *dev, const char ch) 116 { 117 struct msm_serial_data *priv = dev_get_priv(dev); 118 119 if (!(readl(priv->base + UARTDM_SR) & UARTDM_SR_TX_EMPTY) && 120 !(readl(priv->base + UARTDM_ISR) & UARTDM_ISR_TX_READY)) 121 return -EAGAIN; 122 123 writel(UARTDM_CR_CMD_RESET_TX_READY, priv->base + UARTDM_CR); 124 125 writel(1, priv->base + UARTDM_NCF_TX); 126 writel(ch, priv->base + UARTDM_TF); 127 128 return 0; 129 } 130 131 static int msm_serial_pending(struct udevice *dev, bool input) 132 { 133 if (input) { 134 if (msm_serial_fetch(dev)) 135 return 1; 136 } 137 138 return 0; 139 } 140 141 static const struct dm_serial_ops msm_serial_ops = { 142 .putc = msm_serial_putc, 143 .pending = msm_serial_pending, 144 .getc = msm_serial_getc, 145 }; 146 147 static int msm_uart_clk_init(struct udevice *dev) 148 { 149 uint clk_rate = fdtdec_get_uint(gd->fdt_blob, dev->of_offset, 150 "clock-frequency", 115200); 151 uint clkd[2]; /* clk_id and clk_no */ 152 int clk_offset; 153 struct udevice *clk_dev; 154 struct clk clk; 155 int ret; 156 157 ret = fdtdec_get_int_array(gd->fdt_blob, dev->of_offset, "clock", clkd, 158 2); 159 if (ret) 160 return ret; 161 162 clk_offset = fdt_node_offset_by_phandle(gd->fdt_blob, clkd[0]); 163 if (clk_offset < 0) 164 return clk_offset; 165 166 ret = uclass_get_device_by_of_offset(UCLASS_CLK, clk_offset, &clk_dev); 167 if (ret) 168 return ret; 169 170 clk.id = clkd[1]; 171 ret = clk_request(clk_dev, &clk); 172 if (ret < 0) 173 return ret; 174 175 ret = clk_set_rate(&clk, clk_rate); 176 clk_free(&clk); 177 if (ret < 0) 178 return ret; 179 180 return 0; 181 } 182 183 static int msm_serial_probe(struct udevice *dev) 184 { 185 struct msm_serial_data *priv = dev_get_priv(dev); 186 187 msm_uart_clk_init(dev); /* Ignore return value and hope clock was 188 properly initialized by earlier loaders */ 189 190 if (readl(priv->base + UARTDM_SR) & UARTDM_SR_UART_OVERRUN) 191 writel(UARTDM_CR_CMD_RESET_ERR, priv->base + UARTDM_CR); 192 193 writel(0, priv->base + UARTDM_IMR); 194 writel(UARTDM_CR_CMD_STALE_EVENT_DISABLE, priv->base + UARTDM_CR); 195 msm_serial_fetch(dev); 196 197 return 0; 198 } 199 200 static int msm_serial_ofdata_to_platdata(struct udevice *dev) 201 { 202 struct msm_serial_data *priv = dev_get_priv(dev); 203 204 priv->base = dev_get_addr(dev); 205 if (priv->base == FDT_ADDR_T_NONE) 206 return -EINVAL; 207 208 return 0; 209 } 210 211 static const struct udevice_id msm_serial_ids[] = { 212 { .compatible = "qcom,msm-uartdm-v1.4" }, 213 { } 214 }; 215 216 U_BOOT_DRIVER(serial_msm) = { 217 .name = "serial_msm", 218 .id = UCLASS_SERIAL, 219 .of_match = msm_serial_ids, 220 .ofdata_to_platdata = msm_serial_ofdata_to_platdata, 221 .priv_auto_alloc_size = sizeof(struct msm_serial_data), 222 .probe = msm_serial_probe, 223 .ops = &msm_serial_ops, 224 }; 225