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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_core.h>
 25 #include <linux/serial_reg.h>
 26 #include <linux/platform_device.h>
 27 #include <linux/clk.h>
 28 #include <linux/slab.h>
 29 
 30 #include "8250.h"
 31 
 32 #define UART_DLL_EM 9
 33 #define UART_DLM_EM 10
 34 
 35 struct serial8250_em_priv {
 36         struct clk *sclk;
 37         int line;
 38 };
 39 
 40 static void serial8250_em_serial_out(struct uart_port *p, int offset, int value)
 41 {
 42         switch (offset) {
 43         case UART_TX: /* TX @ 0x00 */
 44                 writeb(value, p->membase);
 45                 break;
 46         case UART_FCR: /* FCR @ 0x0c (+1) */
 47         case UART_LCR: /* LCR @ 0x10 (+1) */
 48         case UART_MCR: /* MCR @ 0x14 (+1) */
 49         case UART_SCR: /* SCR @ 0x20 (+1) */
 50                 writel(value, p->membase + ((offset + 1) << 2));
 51                 break;
 52         case UART_IER: /* IER @ 0x04 */
 53                 value &= 0x0f; /* only 4 valid bits - not Xscale */
 54                 /* fall-through */
 55         case UART_DLL_EM: /* DLL @ 0x24 (+9) */
 56         case UART_DLM_EM: /* DLM @ 0x28 (+9) */
 57                 writel(value, p->membase + (offset << 2));
 58         }
 59 }
 60 
 61 static unsigned int serial8250_em_serial_in(struct uart_port *p, int offset)
 62 {
 63         switch (offset) {
 64         case UART_RX: /* RX @ 0x00 */
 65                 return readb(p->membase);
 66         case UART_MCR: /* MCR @ 0x14 (+1) */
 67         case UART_LSR: /* LSR @ 0x18 (+1) */
 68         case UART_MSR: /* MSR @ 0x1c (+1) */
 69         case UART_SCR: /* SCR @ 0x20 (+1) */
 70                 return readl(p->membase + ((offset + 1) << 2));
 71         case UART_IER: /* IER @ 0x04 */
 72         case UART_IIR: /* IIR @ 0x08 */
 73         case UART_DLL_EM: /* DLL @ 0x24 (+9) */
 74         case UART_DLM_EM: /* DLM @ 0x28 (+9) */
 75                 return readl(p->membase + (offset << 2));
 76         }
 77         return 0;
 78 }
 79 
 80 static int serial8250_em_serial_dl_read(struct uart_8250_port *up)
 81 {
 82         return serial_in(up, UART_DLL_EM) | serial_in(up, UART_DLM_EM) << 8;
 83 }
 84 
 85 static void serial8250_em_serial_dl_write(struct uart_8250_port *up, int value)
 86 {
 87         serial_out(up, UART_DLL_EM, value & 0xff);
 88         serial_out(up, UART_DLM_EM, value >> 8 & 0xff);
 89 }
 90 
 91 static int serial8250_em_probe(struct platform_device *pdev)
 92 {
 93         struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 94         struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 95         struct serial8250_em_priv *priv;
 96         struct uart_8250_port up;
 97         int ret;
 98 
 99         if (!regs || !irq) {
100                 dev_err(&pdev->dev, "missing registers or irq\n");
101                 return -EINVAL;
102         }
103 
104         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
105         if (!priv) {
106                 dev_err(&pdev->dev, "unable to allocate private data\n");
107                 return -ENOMEM;
108         }
109 
110         priv->sclk = devm_clk_get(&pdev->dev, "sclk");
111         if (IS_ERR(priv->sclk)) {
112                 dev_err(&pdev->dev, "unable to get clock\n");
113                 return PTR_ERR(priv->sclk);
114         }
115 
116         memset(&up, 0, sizeof(up));
117         up.port.mapbase = regs->start;
118         up.port.irq = irq->start;
119         up.port.type = PORT_UNKNOWN;
120         up.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_IOREMAP;
121         up.port.dev = &pdev->dev;
122         up.port.private_data = priv;
123 
124         clk_prepare_enable(priv->sclk);
125         up.port.uartclk = clk_get_rate(priv->sclk);
126 
127         up.port.iotype = UPIO_MEM32;
128         up.port.serial_in = serial8250_em_serial_in;
129         up.port.serial_out = serial8250_em_serial_out;
130         up.dl_read = serial8250_em_serial_dl_read;
131         up.dl_write = serial8250_em_serial_dl_write;
132 
133         ret = serial8250_register_8250_port(&up);
134         if (ret < 0) {
135                 dev_err(&pdev->dev, "unable to register 8250 port\n");
136                 clk_disable_unprepare(priv->sclk);
137                 return ret;
138         }
139 
140         priv->line = ret;
141         platform_set_drvdata(pdev, priv);
142         return 0;
143 }
144 
145 static int serial8250_em_remove(struct platform_device *pdev)
146 {
147         struct serial8250_em_priv *priv = platform_get_drvdata(pdev);
148 
149         serial8250_unregister_port(priv->line);
150         clk_disable_unprepare(priv->sclk);
151         return 0;
152 }
153 
154 static const struct of_device_id serial8250_em_dt_ids[] = {
155         { .compatible = "renesas,em-uart", },
156         {},
157 };
158 MODULE_DEVICE_TABLE(of, serial8250_em_dt_ids);
159 
160 static struct platform_driver serial8250_em_platform_driver = {
161         .driver = {
162                 .name           = "serial8250-em",
163                 .of_match_table = serial8250_em_dt_ids,
164                 .owner          = THIS_MODULE,
165         },
166         .probe                  = serial8250_em_probe,
167         .remove                 = serial8250_em_remove,
168 };
169 
170 module_platform_driver(serial8250_em_platform_driver);
171 
172 MODULE_AUTHOR("Magnus Damm");
173 MODULE_DESCRIPTION("Renesas Emma Mobile 8250 Driver");
174 MODULE_LICENSE("GPL v2");
175 

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