Re: [PATCH v1] serial: npcm: Add support for Nuvoton NPCM SoCs

Hi Stanley,

On Sun, 16 Jan 2022 at 20:20, Stanley Chu stanley.chuys@gmail.com wrote:

Add Nuvoton BMC NPCM7xx/NPCM8xx uart driver

Signed-off-by: Stanley Chu yschu@nuvoton.com

drivers/serial/Kconfig | 7 ++ drivers/serial/Makefile | 1 + drivers/serial/serial_npcm.c | 151 +++++++++++++++++++++++++++++++++++ 3 files changed, 159 insertions(+) create mode 100644 drivers/serial/serial_npcm.c

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig index 6c8fdda9a0..8daaef61b3 100644 --- a/drivers/serial/Kconfig +++ b/drivers/serial/Kconfig @@ -920,6 +920,13 @@ config MPC8XX_CONS depends on MPC8xx default y

+config NPCM_SERIAL

•   bool "UART driver for Nuvoton NPCM BMC"
  

•   depends on DM_SERIAL
  

•   help
  

•     Select this to enable UART support for Nuvoton BMCs
  

•     (NPCM7xx and NPCM8xx)
  

What features does it support? Please expand this a bit.

config XEN_SERIAL bool "XEN serial support" depends on XEN diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile index 8168af640f..866495e416 100644 --- a/drivers/serial/Makefile +++ b/drivers/serial/Makefile @@ -73,6 +73,7 @@ obj-$(CONFIG_OWL_SERIAL) += serial_owl.o obj-$(CONFIG_OMAP_SERIAL) += serial_omap.o obj-$(CONFIG_MTK_SERIAL) += serial_mtk.o obj-$(CONFIG_MT7620_SERIAL) += serial_mt7620.o +obj-$(CONFIG_NPCM_SERIAL) += serial_npcm.o obj-$(CONFIG_SIFIVE_SERIAL) += serial_sifive.o obj-$(CONFIG_XEN_SERIAL) += serial_xen.o

diff --git a/drivers/serial/serial_npcm.c b/drivers/serial/serial_npcm.c new file mode 100644 index 0000000000..67343e5805 --- /dev/null +++ b/drivers/serial/serial_npcm.c @@ -0,0 +1,151 @@ +// SPDX-License-Identifier: GPL-2.0+ +/*

• • Copyright (c) 2021 Nuvoton Technology Corp.
• */

+#include <common.h> +#include <clk.h> +#include <dm.h> +#include <serial.h>

+struct npcm_uart {

•   union {
  

•           u32     rbr;
  

•           u32     thr;
  

•           u32     dll;
  

•   };
  

•   union {
  

•           u32     ier;
  

•           u32     dlm;
  

•   };
  

•   union {
  

•           u32     iir;
  

•           u32     fcr;
  

•   };
  

•   u32     lcr;
  

•   u32     mcr;
  

•   u32     lsr;
  

•   u32     msr;
  

•   u32     tor;
  

+};

+#define LCR_WLS_8BITS 3 +#define FCR_TFR BIT(2) +#define FCR_RFR BIT(1) +#define FCR_FME BIT(0) +#define LSR_THRE BIT(5) +#define LSR_RFDR BIT(0) +#define LCR_DLAB BIT(7)

+struct npcm_serial_plat {

•   struct npcm_uart *reg;
  

•   u32 uart_clk;
  

comment that

+};

+static int npcm_serial_pending(struct udevice *dev, bool input) +{

•   struct npcm_serial_plat *plat = dev_get_plat(dev);
  

•   struct npcm_uart *uart = plat->reg;
  

•   if (input)
  

•           return (readb(&uart->lsr) & LSR_RFDR);
  

drop outer brackets

•   else
  

•           return !(readb(&uart->lsr) & LSR_THRE);
  

and here

+}

+static int npcm_serial_putc(struct udevice *dev, const char ch) +{

•   struct npcm_serial_plat *plat = dev_get_plat(dev);
  

•   struct npcm_uart *uart = plat->reg;
  

•   while (!(readb(&uart->lsr) & LSR_THRE))
  

•           ;
  

You cannot loop here. Return -EAGAIN instead if you cannot print.

•   writeb(ch, &uart->thr);
  

•   return 0;
  

+}

+static int npcm_serial_getc(struct udevice *dev) +{

•   struct npcm_serial_plat *plat = dev_get_plat(dev);
  

•   struct npcm_uart *uart = plat->reg;
  

•   while (!(readb(&uart->lsr) & LSR_RFDR))
  

•           ;
  

You cannot loop here. Return -EAGAIN instead. See __serial_getc()

•   return readb(&uart->rbr);
  

+}

+static int npcm_serial_setbrg(struct udevice *dev, int baudrate) +{

•   struct npcm_serial_plat *plat = dev_get_plat(dev);
  

•   struct npcm_uart *uart = plat->reg;
  

•   u16 divisor;
  

•   /* BaudOut = UART Clock  / (16 * [Divisor + 2]) */
  

•   divisor = DIV_ROUND_CLOSEST(plat->uart_clk, 16 * baudrate + 2) - 2;
  

•   setbits_8(&uart->lcr, LCR_DLAB);
  

•   writeb(divisor & 0xff, &uart->dll);
  

•   writeb(divisor >> 8, &uart->dlm);
  

•   clrbits_8(&uart->lcr, LCR_DLAB);
  

•   return 0;
  

+}

+static int npcm_serial_probe(struct udevice *dev) +{

•   struct npcm_serial_plat *plat = dev_get_plat(dev);
  

•   struct npcm_uart *uart = plat->reg;
  

•   struct clk clk;
  

•   u32 freq;
  

•   int ret;
  

•   plat->reg = dev_read_addr_ptr(dev);
  

•   freq = dev_read_u32_default(dev, "clock-frequency", 0);
  

•   ret = clk_get_by_index(dev, 0, &clk);
  

•   if (ret < 0) {
  

•           printf("Cannot get clk for uart\n");
  

log_debug() would be better to avoid increasing code size

•           return ret;
  

•   }
  

•   ret = clk_set_rate(&clk, freq);
  

•   if (ret < 0)
  

•           return ret;
  

•   plat->uart_clk = ret;
  

•   /* Disable all interrupt */
  

•   writeb(0, &uart->ier);
  

•   /* Set 8 bit, 1 stop, no parity */
  

•   writeb(LCR_WLS_8BITS, &uart->lcr);
  

•   /* Reset RX/TX FIFO */
  

•   writeb(FCR_FME | FCR_RFR | FCR_TFR, &uart->fcr);
  

•   return 0;
  

+}

+static const struct dm_serial_ops npcm_serial_ops = {

•   .getc = npcm_serial_getc,
  

•   .setbrg = npcm_serial_setbrg,
  

•   .putc = npcm_serial_putc,
  

•   .pending = npcm_serial_pending,
  

+};

+static const struct udevice_id npcm_serial_ids[] = {

•   { .compatible = "nuvoton,npcm750-uart" },
  

•   { .compatible = "nuvoton,npcm845-uart" },
  

•   { }
  

+};

+U_BOOT_DRIVER(serial_npcm) = {

•   .name   = "serial_npcm",
  

•   .id     = UCLASS_SERIAL,
  

•   .of_match = npcm_serial_ids,
  

•   .plat_auto  = sizeof(struct npcm_serial_plat),
  

•   .probe = npcm_serial_probe,
  

•   .ops    = &npcm_serial_ops,
  

•   .flags = DM_FLAG_PRE_RELOC,
  

+};

2.17.1

Regards, Simon