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([94.75.70.14]) by smtp.gmail.com with ESMTPSA id er14-20020a05651248ce00b004fdb27909cesm2238855lfb.5.2023.07.24.07.27.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Jul 2023 07:27:22 -0700 (PDT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 352689c8-2a2e-11ee-8612-37d641c3527e DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1690208844; x=1690813644; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=q1pbQAm5Bhfv4qZPL0AfqaY18XN1qs/woa+tmGH403k=; b=GoQiEqjF0SmLWmIsgxxm/vIxFnbNgZ8ii2V62ha214WcDTXeAP1ll9Srfm4aG7BJms OtBW+TiJSSKc/+B2gnbqtpjST3dfUq2hqhlQstiOlVT1SiLR9+WbN55Hzdgm7dmHy9Kj nfSwX2vL3Is9o9veLpxFV7MgseQygTgs/JO6ds6oJG3lzewzoZwesNDFdUdUjZyWwoxB QTipnU4JOssMVfk71TlIiAlo4YpXpTvR023s+zVugfCBrk4v2wd8bFQLcR6g3CaPnT4W wZ+LdvIdw6qenwufBplPtGBvbIm0KDhBfIPASXfALZl++05DogOxD/2bo20NHe204z4d lFKg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690208844; x=1690813644; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=q1pbQAm5Bhfv4qZPL0AfqaY18XN1qs/woa+tmGH403k=; b=KdWDrOrgvr+szM0iyUCtONKc2FUvYUYYCXGIj9GZ191sQeHddC4yOSSjTqrk0nOITE LGFd2r/W0P0WyH178AVSNDTCmPZMly+gzYtQB01nUVj6EOoM3oar8PIp6Qi7WpI2CyO9 5Uwo+AacOPHScr/I3Fpb8TcaSONGMo/lAt5OjAq0J+fzIlgNg1CZoVoHdCsjc/cix59X Wuh8dNj67hcTmv2lwjYxIq5kS0VocEYQ6kfDdEfe4+QYb6wly4RFnWzhTo/bcsVu/J9F IQMQeGBnypIlDd0zKTfZCNH6OOcMMGSQLAvT6YdWmnTmFNI5iBI7zmYh6F66+1wNvak2 KCug== X-Gm-Message-State: ABy/qLZoNkPrAMXA7OXsNbT0Vz3iM/D60FgC0WaPWpiG4jCg1DEZWUKJ 3V+6QwoRJ1qFxpLCnqv+NOEFfQZePH0= X-Google-Smtp-Source: APBJJlEJXrjV48nVMGFDzOAX/eTdjirm2w57RDngn0Zz/VLj+f0iLcnVCd/SlpCT8FFwqhKhSfRNCw== X-Received: by 2002:ac2:4d07:0:b0:4fb:a088:cfca with SMTP id r7-20020ac24d07000000b004fba088cfcamr3347618lfi.6.1690208843344; Mon, 24 Jul 2023 07:27:23 -0700 (PDT) From: Oleksii Kurochko To: xen-devel@lists.xenproject.org Cc: Oleksii Kurochko , Andrew Cooper , George Dunlap , Jan Beulich , Julien Grall , Stefano Stabellini , Wei Liu Subject: [PATCH v3] ns16550: add support for polling mode when device tree is used Date: Mon, 24 Jul 2023 17:27:20 +0300 Message-ID: X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 RISC-V doesn't support interrupts for the time being, so it would be nice to have polling mode. The patch adds new option to console='...,polling' which forces driver to use polling mode. If there is no interrupt property in UART node, then polling will be used.     According to 4.2.2 National Semiconductor 16450/16550 Compatible UART Requirements from The Devicetree Specification v0.4 ( https://www.devicetree.org/specifications/ ) the interrupt property is         optional. Also, it is possible that interrupt '0' can be used for some architectures as an legal UART interrupt number ( according to dts files in Linux kernel ), so the check of the return value of platform_get_irq() was updated in case of when device tree is used for UART initialization. For example: https://github.com/torvalds/linux/blob/master/arch/powerpc/boot/dts/ebony.dts#L197 Signed-off-by: Oleksii Kurochko --- xen/drivers/char/console.c | 2 ++ xen/drivers/char/ns16550.c | 38 ++++++++++++++++++++++++++++---------- 2 files changed, 30 insertions(+), 10 deletions(-) diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c index 0e410fa086..07e9610d77 100644 --- a/xen/drivers/char/console.c +++ b/xen/drivers/char/console.c @@ -993,6 +993,8 @@ void __init console_init_preirq(void) #endif else if ( !strncmp(p, "none", 4) ) continue; + else if ( !strncmp(p, "polling", 7 ) + continue; else if ( (sh = serial_parse_handle(p)) >= 0 ) { sercon_handle = sh; diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c index 2aed6ec707..a6eb3b3997 100644 --- a/xen/drivers/char/ns16550.c +++ b/xen/drivers/char/ns16550.c @@ -58,7 +58,11 @@ static struct ns16550 { struct timer timer; struct timer resume_timer; unsigned int timeout_ms; - bool_t intr_works; + enum { + intr_off, + intr_on, + polling, + } intr_works; bool_t dw_usr_bsy; #ifdef NS16550_PCI /* PCI card parameters. */ @@ -181,7 +185,7 @@ static void cf_check ns16550_interrupt( struct serial_port *port = dev_id; struct ns16550 *uart = port->uart; - uart->intr_works = 1; + uart->intr_works = intr_on; while ( !(ns_read_reg(uart, UART_IIR) & UART_IIR_NOINT) ) { @@ -212,7 +216,7 @@ static void cf_check __ns16550_poll(struct cpu_user_regs *regs) struct serial_port *port = this_cpu(poll_port); struct ns16550 *uart = port->uart; - if ( uart->intr_works ) + if ( uart->intr_works == intr_on ) return; /* Interrupts work - no more polling */ while ( ns_read_reg(uart, UART_LSR) & UART_LSR_DR ) @@ -305,7 +309,8 @@ static void ns16550_setup_preirq(struct ns16550 *uart) unsigned char lcr; unsigned int divisor; - uart->intr_works = 0; + if ( uart->intr_works != polling ) + uart->intr_works = intr_off; pci_serial_early_init(uart); @@ -394,7 +399,7 @@ static void __init cf_check ns16550_init_irq(struct serial_port *port) static void ns16550_setup_postirq(struct ns16550 *uart) { - if ( uart->irq > 0 ) + if ( uart->intr_works != polling ) { /* Master interrupt enable; also keep DTR/RTS asserted. */ ns_write_reg(uart, @@ -473,6 +478,7 @@ static void __init cf_check ns16550_init_postirq(struct serial_port *port) if ( rc ) { uart->irq = 0; + uart->intr_works = polling; if ( msi_desc ) msi_free_irq(msi_desc); else @@ -488,7 +494,7 @@ static void __init cf_check ns16550_init_postirq(struct serial_port *port) } #endif - if ( uart->irq > 0 ) + if ( uart->intr_works != polling ) { uart->irqaction.handler = ns16550_interrupt; uart->irqaction.name = "ns16550"; @@ -595,7 +601,9 @@ static void __init cf_check ns16550_endboot(struct serial_port *port) static int __init cf_check ns16550_irq(struct serial_port *port) { struct ns16550 *uart = port->uart; - return ((uart->irq > 0) ? uart->irq : -1); + + return ( uart->intr_works != polling ) ? + uart->irq : -1; } static void cf_check ns16550_start_tx(struct serial_port *port) @@ -654,6 +662,9 @@ static void ns16550_init_common(struct ns16550 *uart) /* Default lsr_mask = UART_LSR_THRE */ uart->lsr_mask = UART_LSR_THRE; + + if ( console_has("polling") ) + uart->intr_works = polling; } #ifdef CONFIG_X86 @@ -1330,9 +1341,12 @@ pci_uart_config(struct ns16550 *uart, bool_t skip_amt, unsigned int idx) * as special only for X86. */ if ( uart->irq == 0xff ) + { uart->irq = 0; + uart->intr_works = polling; + } #endif - if ( !uart->irq ) + if ( !uart->irq || (uart->intr_works == polling) ) printk(XENLOG_INFO "ns16550: %pp: no legacy IRQ, using poll mode\n", &PCI_SBDF(0, b, d, f)); @@ -1552,6 +1566,7 @@ static bool __init parse_positional(struct ns16550 *uart, char **str) conf += 3; uart->msi = true; uart->irq = 0; + uart->intr_works = polling; } else #endif @@ -1791,8 +1806,11 @@ static int __init ns16550_uart_dt_init(struct dt_device_node *dev, } res = platform_get_irq(dev, 0); - if ( ! res ) - return -EINVAL; + if ( res < 0 ) + { + printk("there is no interrupt property, polling will be used\n"); + uart->intr_works = polling; + } uart->irq = res; uart->dw_usr_bsy = dt_device_is_compatible(dev, "snps,dw-apb-uart");