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[86.9.19.6]) by smtp.gmail.com with ESMTPSA id d143sm3330771wmd.16.2020.04.28.06.54.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Apr 2020 06:54:57 -0700 (PDT) Date: Tue, 28 Apr 2020 14:54:56 +0100 From: Daniel Thompson To: Sumit Garg Cc: dianders@chromium.org, linux-serial@vger.kernel.org, linux@armlinux.org.uk, gregkh@linuxfoundation.org, jslaby@suse.com, jason.wessel@windriver.com, kgdb-bugreport@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH] serial: amba-pl011: Support earlycon_kgdboc Message-ID: <20200428135456.2d7zxz2mdte5kclk@holly.lan> References: <1587716031-28199-1-git-send-email-sumit.garg@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1587716031-28199-1-git-send-email-sumit.garg@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 24, 2020 at 01:43:51PM +0530, Sumit Garg wrote: > Implement the read() function in the early console driver. With > recently added earlycon_kgdboc feature, this allows you to use kgdb > to debug fairly early into the system boot. > > We only bother implementing this if polling is enabled since kgdb can't > be enabled without that. > > Signed-off-by: Sumit Garg Reviewed-by: Daniel Thompson > --- > > Depends on kgdb patch series: https://lkml.org/lkml/2020/4/21/1179 > > drivers/tty/serial/amba-pl011.c | 32 ++++++++++++++++++++++++++++++++ > 1 file changed, 32 insertions(+) > > diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c > index 2296bb0..c010f63 100644 > --- a/drivers/tty/serial/amba-pl011.c > +++ b/drivers/tty/serial/amba-pl011.c > @@ -2435,6 +2435,37 @@ static void pl011_early_write(struct console *con, const char *s, unsigned n) > uart_console_write(&dev->port, s, n, pl011_putc); > } > > +#ifdef CONFIG_CONSOLE_POLL > +static int pl011_getc(struct uart_port *port) > +{ > + if (readl(port->membase + UART01x_FR) & UART01x_FR_RXFE) > + return NO_POLL_CHAR; > + > + if (port->iotype == UPIO_MEM32) > + return readl(port->membase + UART01x_DR); > + else > + return readb(port->membase + UART01x_DR); > +} > + > +static int pl011_early_read(struct console *con, char *s, unsigned int n) > +{ > + struct earlycon_device *dev = con->data; > + int ch, num_read = 0; > + > + while (num_read < n) { > + ch = pl011_getc(&dev->port); > + if (ch == NO_POLL_CHAR) > + break; > + > + s[num_read++] = ch; > + } > + > + return num_read; > +} > +#else > +#define pl011_early_read NULL > +#endif > + > /* > * On non-ACPI systems, earlycon is enabled by specifying > * "earlycon=pl011,
" on the kernel command line. > @@ -2454,6 +2485,7 @@ static int __init pl011_early_console_setup(struct earlycon_device *device, > return -ENODEV; > > device->con->write = pl011_early_write; > + device->con->read = pl011_early_read; > > return 0; > } > -- > 2.7.4 >