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Linux/drivers/tty/serial/8250/8250_em.c

  1 /*
  2  * Renesas Emma Mobile 8250 driver
  3  *
  4  *  Copyright (C) 2012 Magnus Damm
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License as published by
  8  * the Free Software Foundation; either version 2 of the License
  9  *
 10  * This program is distributed in the hope that it will be useful,
 11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13  * GNU General Public License for more details.
 14  *
 15  * You should have received a copy of the GNU General Public License
 16  * along with this program; if not, write to the Free Software
 17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 18  */
 19 
 20 #include <linux/device.h>
 21 #include <linux/io.h>
 22 #include <linux/module.h>
 23 #include <linux/serial_8250.h>
 24 #include <linux/serial_reg.h>
 25 #include <linux/platform_device.h>
 26 #include <linux/clk.h>
 27 #include <linux/slab.h>
 28 
 29 #include "8250.h"
 30 
 31 #define UART_DLL_EM 9
 32 #define UART_DLM_EM 10
 33 
 34 struct serial8250_em_priv {
 35         struct clk *sclk;
 36         int line;
 37 };
 38 
 39 static void serial8250_em_serial_out(struct uart_port *p, int offset, int value)
 40 {
 41         switch (offset) {
 42         case UART_TX: /* TX @ 0x00 */
 43                 writeb(value, p->membase);
 44                 break;
 45         case UART_FCR: /* FCR @ 0x0c (+1) */
 46         case UART_LCR: /* LCR @ 0x10 (+1) */
 47         case UART_MCR: /* MCR @ 0x14 (+1) */
 48         case UART_SCR: /* SCR @ 0x20 (+1) */
 49                 writel(value, p->membase + ((offset + 1) << 2));
 50                 break;
 51         case UART_IER: /* IER @ 0x04 */
 52                 value &= 0x0f; /* only 4 valid bits - not Xscale */
 53                 /* fall-through */
 54         case UART_DLL_EM: /* DLL @ 0x24 (+9) */
 55         case UART_DLM_EM: /* DLM @ 0x28 (+9) */
 56                 writel(value, p->membase + (offset << 2));
 57         }
 58 }
 59 
 60 static unsigned int serial8250_em_serial_in(struct uart_port *p, int offset)
 61 {
 62         switch (offset) {
 63         case UART_RX: /* RX @ 0x00 */
 64                 return readb(p->membase);
 65         case UART_MCR: /* MCR @ 0x14 (+1) */
 66         case UART_LSR: /* LSR @ 0x18 (+1) */
 67         case UART_MSR: /* MSR @ 0x1c (+1) */
 68         case UART_SCR: /* SCR @ 0x20 (+1) */
 69                 return readl(p->membase + ((offset + 1) << 2));
 70         case UART_IER: /* IER @ 0x04 */
 71         case UART_IIR: /* IIR @ 0x08 */
 72         case UART_DLL_EM: /* DLL @ 0x24 (+9) */
 73         case UART_DLM_EM: /* DLM @ 0x28 (+9) */
 74                 return readl(p->membase + (offset << 2));
 75         }
 76         return 0;
 77 }
 78 
 79 static int serial8250_em_serial_dl_read(struct uart_8250_port *up)
 80 {
 81         return serial_in(up, UART_DLL_EM) | serial_in(up, UART_DLM_EM) << 8;
 82 }
 83 
 84 static void serial8250_em_serial_dl_write(struct uart_8250_port *up, int value)
 85 {
 86         serial_out(up, UART_DLL_EM, value & 0xff);
 87         serial_out(up, UART_DLM_EM, value >> 8 & 0xff);
 88 }
 89 
 90 static int serial8250_em_probe(struct platform_device *pdev)
 91 {
 92         struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 93         struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 94         struct serial8250_em_priv *priv;
 95         struct uart_8250_port up;
 96         int ret;
 97 
 98         if (!regs || !irq) {
 99                 dev_err(&pdev->dev, "missing registers or irq\n");
100                 return -EINVAL;
101         }
102 
103         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
104         if (!priv)
105                 return -ENOMEM;
106 
107         priv->sclk = devm_clk_get(&pdev->dev, "sclk");
108         if (IS_ERR(priv->sclk)) {
109                 dev_err(&pdev->dev, "unable to get clock\n");
110                 return PTR_ERR(priv->sclk);
111         }
112 
113         memset(&up, 0, sizeof(up));
114         up.port.mapbase = regs->start;
115         up.port.irq = irq->start;
116         up.port.type = PORT_UNKNOWN;
117         up.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_IOREMAP;
118         up.port.dev = &pdev->dev;
119         up.port.private_data = priv;
120 
121         clk_prepare_enable(priv->sclk);
122         up.port.uartclk = clk_get_rate(priv->sclk);
123 
124         up.port.iotype = UPIO_MEM32;
125         up.port.serial_in = serial8250_em_serial_in;
126         up.port.serial_out = serial8250_em_serial_out;
127         up.dl_read = serial8250_em_serial_dl_read;
128         up.dl_write = serial8250_em_serial_dl_write;
129 
130         ret = serial8250_register_8250_port(&up);
131         if (ret < 0) {
132                 dev_err(&pdev->dev, "unable to register 8250 port\n");
133                 clk_disable_unprepare(priv->sclk);
134                 return ret;
135         }
136 
137         priv->line = ret;
138         platform_set_drvdata(pdev, priv);
139         return 0;
140 }
141 
142 static int serial8250_em_remove(struct platform_device *pdev)
143 {
144         struct serial8250_em_priv *priv = platform_get_drvdata(pdev);
145 
146         serial8250_unregister_port(priv->line);
147         clk_disable_unprepare(priv->sclk);
148         return 0;
149 }
150 
151 static const struct of_device_id serial8250_em_dt_ids[] = {
152         { .compatible = "renesas,em-uart", },
153         {},
154 };
155 MODULE_DEVICE_TABLE(of, serial8250_em_dt_ids);
156 
157 static struct platform_driver serial8250_em_platform_driver = {
158         .driver = {
159                 .name           = "serial8250-em",
160                 .of_match_table = serial8250_em_dt_ids,
161         },
162         .probe                  = serial8250_em_probe,
163         .remove                 = serial8250_em_remove,
164 };
165 
166 module_platform_driver(serial8250_em_platform_driver);
167 
168 MODULE_AUTHOR("Magnus Damm");
169 MODULE_DESCRIPTION("Renesas Emma Mobile 8250 Driver");
170 MODULE_LICENSE("GPL v2");
171 

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