arch/arm/mach-lpc32xx/serial.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * arch/arm/mach-lpc32xx/serial.c
   4  *
   5  * Author: Kevin Wells <kevin.wells@nxp.com>
   6  *
   7  * Copyright (C) 2010 NXP Semiconductors
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/types.h>
  12 #include <linux/serial.h>
  13 #include <linux/serial_core.h>
  14 #include <linux/serial_reg.h>
  15 #include <linux/serial_8250.h>
  16 #include <linux/clk.h>
  17 #include <linux/io.h>
  18 #include <linux/soc/nxp/lpc32xx-misc.h>
  19
  20 #include "lpc32xx.h"
  21 #include "common.h"
  22
  23 #define LPC32XX_SUART_FIFO_SIZE 64
  24
  25 struct uartinit {
  26         char *uart_ck_name;
  27         u32 ck_mode_mask;
  28         void __iomem *pdiv_clk_reg;
  29         resource_size_t mapbase;
  30 };
  31
  32 static struct uartinit uartinit_data[] __initdata = {
  33         {
  34                 .uart_ck_name = "uart5_ck",
  35                 .ck_mode_mask =
  36                         LPC32XX_UART_CLKMODE_LOAD(LPC32XX_UART_CLKMODE_ON, 5),
  37                 .pdiv_clk_reg = LPC32XX_CLKPWR_UART5_CLK_CTRL,
  38                 .mapbase = LPC32XX_UART5_BASE,
  39         },
  40         {
  41                 .uart_ck_name = "uart3_ck",
  42                 .ck_mode_mask =
  43                         LPC32XX_UART_CLKMODE_LOAD(LPC32XX_UART_CLKMODE_ON, 3),
  44                 .pdiv_clk_reg = LPC32XX_CLKPWR_UART3_CLK_CTRL,
  45                 .mapbase = LPC32XX_UART3_BASE,
  46         },
  47         {
  48                 .uart_ck_name = "uart4_ck",
  49                 .ck_mode_mask =
  50                         LPC32XX_UART_CLKMODE_LOAD(LPC32XX_UART_CLKMODE_ON, 4),
  51                 .pdiv_clk_reg = LPC32XX_CLKPWR_UART4_CLK_CTRL,
  52                 .mapbase = LPC32XX_UART4_BASE,
  53         },
  54         {
  55                 .uart_ck_name = "uart6_ck",
  56                 .ck_mode_mask =
  57                         LPC32XX_UART_CLKMODE_LOAD(LPC32XX_UART_CLKMODE_ON, 6),
  58                 .pdiv_clk_reg = LPC32XX_CLKPWR_UART6_CLK_CTRL,
  59                 .mapbase = LPC32XX_UART6_BASE,
  60         },
  61 };
  62
  63 /* LPC3250 Errata HSUART.1: Hang workaround via loopback mode on inactivity */
  64 void lpc32xx_loopback_set(resource_size_t mapbase, int state)
  65 {
  66         int bit;
  67         u32 tmp;
  68
  69         switch (mapbase) {
  70         case LPC32XX_HS_UART1_BASE:
  71                 bit = 0;
  72                 break;
  73         case LPC32XX_HS_UART2_BASE:
  74                 bit = 1;
  75                 break;
  76         case LPC32XX_HS_UART7_BASE:
  77                 bit = 6;
  78                 break;
  79         default:
  80                 WARN(1, "lpc32xx_hs: Warning: Unknown port at %08x\n", mapbase);
  81                 return;
  82         }
  83
  84         tmp = readl(LPC32XX_UARTCTL_CLOOP);
  85         if (state)
  86                 tmp |= (1 << bit);
  87         else
  88                 tmp &= ~(1 << bit);
  89         writel(tmp, LPC32XX_UARTCTL_CLOOP);
  90 }
  91 EXPORT_SYMBOL_GPL(lpc32xx_loopback_set);
  92
  93 void __init lpc32xx_serial_init(void)
  94 {
  95         u32 tmp, clkmodes = 0;
  96         struct clk *clk;
  97         unsigned int puart;
  98         int i, j;
  99
 100         for (i = 0; i < ARRAY_SIZE(uartinit_data); i++) {
 101                 clk = clk_get(NULL, uartinit_data[i].uart_ck_name);
 102                 if (!IS_ERR(clk)) {
 103                         clk_enable(clk);
 104                 }
 105
 106                 /* Setup UART clock modes for all UARTs, disable autoclock */
 107                 clkmodes |= uartinit_data[i].ck_mode_mask;
 108
 109                 /* pre-UART clock divider set to 1 */
 110                 __raw_writel(0x0101, uartinit_data[i].pdiv_clk_reg);
 111
 112                 /*
 113                  * Force a flush of the RX FIFOs to work around a
 114                  * HW bug
 115                  */
 116                 puart = uartinit_data[i].mapbase;
 117                 __raw_writel(0xC1, LPC32XX_UART_IIR_FCR(puart));
 118                 __raw_writel(0x00, LPC32XX_UART_DLL_FIFO(puart));
 119                 j = LPC32XX_SUART_FIFO_SIZE;
 120                 while (j--)
 121                         tmp = __raw_readl(
 122                                 LPC32XX_UART_DLL_FIFO(puart));
 123                 __raw_writel(0, LPC32XX_UART_IIR_FCR(puart));
 124         }
 125
 126         /* This needs to be done after all UART clocks are setup */
 127         __raw_writel(clkmodes, LPC32XX_UARTCTL_CLKMODE);
 128         for (i = 0; i < ARRAY_SIZE(uartinit_data); i++) {
 129                 /* Force a flush of the RX FIFOs to work around a HW bug */
 130                 puart = uartinit_data[i].mapbase;
 131                 __raw_writel(0xC1, LPC32XX_UART_IIR_FCR(puart));
 132                 __raw_writel(0x00, LPC32XX_UART_DLL_FIFO(puart));
 133                 j = LPC32XX_SUART_FIFO_SIZE;
 134                 while (j--)
 135                         tmp = __raw_readl(LPC32XX_UART_DLL_FIFO(puart));
 136                 __raw_writel(0, LPC32XX_UART_IIR_FCR(puart));
 137         }
 138
 139         /* Disable IrDA pulsing support on UART6 */
 140         tmp = __raw_readl(LPC32XX_UARTCTL_CTRL);
 141         tmp |= LPC32XX_UART_UART6_IRDAMOD_BYPASS;
 142         __raw_writel(tmp, LPC32XX_UARTCTL_CTRL);
 143
 144         /* Disable UART5->USB transparent mode or USB won't work */
 145         tmp = __raw_readl(LPC32XX_UARTCTL_CTRL);
 146         tmp &= ~LPC32XX_UART_U5_ROUTE_TO_USB;
 147         __raw_writel(tmp, LPC32XX_UARTCTL_CTRL);
 148 }