git.openwrt.org Git - openwrt/staging/linusw.git/blob

   1 From d9d113c22c634219cc248a7c6dcf157e2927edad Mon Sep 17 00:00:00 2001
   2 From: Fugang Duan <fugang.duan@nxp.com>
   3 Date: Tue, 23 Jul 2019 11:36:22 +0800
   4 Subject: [PATCH] MLK-21445 serial: fsl_lpuart: do HW reset for communication
   5  port
   6
   7 Do HW reset for communication port after the port is registered
   8 if the UART controller support the feature.
   9
  10 Do partition reset with LPUART's power on, LPUART registers will
  11 keep the previous status, like on i.MX8QM platform,  which is not
  12 expected action, so reset the HW is required.
  13
  14 Currently, only i.MX7ULP and i.MX8QM LPUART controllers include
  15 global register that support HW reset.
  16
  17 Tested-by: Robin Gong <yibin.gong@nxp.com>
  18 Tested-by: Peng Fan <peng.fan@nxp.com>
  19 Reviewed-by: Robby Cai <robby.cai@nxp.com>
  20 Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
  21 (cherry picked from commit c2bc1f62ec28981462c9cb5ceac17134931ca19f)
  22 Signed-off-by: Arulpandiyan Vadivel <arulpandiyan_vadivel@mentor.com>
  23 Signed-off-by: Shrikant Bobade <Shrikant_Bobade@mentor.com>
  24 (cherry picked from commit 9f396f540093402317c3c1b9a8fe955b91c89164)
  25 ---
  26  drivers/tty/serial/fsl_lpuart.c | 48 +++++++++++++++++++++++++++++++++++++++++
  27  1 file changed, 48 insertions(+)
  28
  29 --- a/drivers/tty/serial/fsl_lpuart.c
  30 +++ b/drivers/tty/serial/fsl_lpuart.c
  31 @@ -11,6 +11,7 @@
  32
  33  #include <linux/clk.h>
  34  #include <linux/console.h>
  35 +#include <linux/delay.h>
  36  #include <linux/dma-mapping.h>
  37  #include <linux/dmaengine.h>
  38  #include <linux/dmapool.h>
  39 @@ -116,6 +117,11 @@
  40  #define UARTSFIFO_TXOF         0x02
  41  #define UARTSFIFO_RXUF         0x01
  42
  43 +/* 32-bit global registers only for i.MX7ulp/MX8x
  44 + * The driver only use the reset feature to reset HW.
  45 + */
  46 +#define UART_GLOBAL            0x8
  47 +
  48  /* 32-bit register definition */
  49  #define UARTBAUD               0x00
  50  #define UARTSTAT               0x04
  51 @@ -230,6 +236,10 @@
  52  #define UARTWATER_TXWATER_OFF  0
  53  #define UARTWATER_RXWATER_OFF  16
  54
  55 +#define UART_GLOBAL_RST                0x2
  56 +#define RST_HW_MIN_US          20
  57 +#define RST_HW_MAX_US          40
  58 +
  59  #define UARTFIFO_RXIDEN_RDRF   0x3
  60  #define UARTCTRL_IDLECFG       0x7
  61
  62 @@ -350,6 +360,11 @@ static inline bool is_layerscape_lpuart(
  63                 sport->devtype == LS1028A_LPUART);
  64  }
  65
  66 +static inline bool is_imx7ulp_lpuart(struct lpuart_port *sport)
  67 +{
  68 +       return sport->devtype == IMX7ULP_LPUART;
  69 +}
  70 +
  71  static inline bool is_imx8qxp_lpuart(struct lpuart_port *sport)
  72  {
  73         return sport->devtype == IMX8QXP_LPUART;
  74 @@ -413,6 +428,33 @@ static unsigned int lpuart_get_baud_clk_
  75  #define lpuart_enable_clks(x)  __lpuart_enable_clks(x, true)
  76  #define lpuart_disable_clks(x) __lpuart_enable_clks(x, false)
  77
  78 +static int lpuart_hw_reset(struct lpuart_port *sport)
  79 +{
  80 +       struct uart_port *port = &sport->port;
  81 +       void __iomem *global_addr;
  82 +       int ret;
  83 +
  84 +       if (uart_console(port))
  85 +               return 0;
  86 +
  87 +       ret = clk_prepare_enable(sport->ipg_clk);
  88 +       if (ret) {
  89 +               dev_err(sport->port.dev, "failed to enable uart ipg clk: %d\n", ret);
  90 +               return ret;
  91 +       }
  92 +
  93 +       if (is_imx7ulp_lpuart(sport) || is_imx8qxp_lpuart(sport)) {
  94 +               global_addr = port->membase + UART_GLOBAL - IMX_REG_OFF;
  95 +               writel(UART_GLOBAL_RST, global_addr);
  96 +               usleep_range(RST_HW_MIN_US, RST_HW_MAX_US);
  97 +               writel(0, global_addr);
  98 +               usleep_range(RST_HW_MIN_US, RST_HW_MAX_US);
  99 +       }
 100 +
 101 +       clk_disable_unprepare(sport->ipg_clk);
 102 +       return 0;
 103 +}
 104 +
 105  static void lpuart_stop_tx(struct uart_port *port)
 106  {
 107         unsigned char temp;
 108 @@ -2728,6 +2770,10 @@ static int lpuart_probe(struct platform_
 109         if (ret)
 110                 goto failed_attach_port;
 111
 112 +       ret = lpuart_hw_reset(sport);
 113 +       if (ret)
 114 +               goto failed_reset;
 115 +
 116         uart_get_rs485_mode(&pdev->dev, &sport->port.rs485);
 117
 118         if (sport->port.rs485.flags & SER_RS485_RX_DURING_TX)
 119 @@ -2751,6 +2797,8 @@ static int lpuart_probe(struct platform_
 120
 121         return 0;
 122
 123 +failed_reset:
 124 +       uart_remove_one_port(&lpuart_reg, &sport->port);
 125  failed_attach_port:
 126  failed_irq_request:
 127         lpuart_disable_clks(sport);