From patchwork Mon May 8 08:20:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tony Lindgren X-Patchwork-Id: 13234229 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 012D3C7EE2A for ; Mon, 8 May 2023 08:20:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229999AbjEHIUh (ORCPT ); Mon, 8 May 2023 04:20:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44862 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233587AbjEHIUg (ORCPT ); Mon, 8 May 2023 04:20:36 -0400 Received: from muru.com (muru.com [72.249.23.125]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 414521C0CC; Mon, 8 May 2023 01:20:35 -0700 (PDT) Received: from hillo.muru.com (localhost [127.0.0.1]) by muru.com (Postfix) with ESMTP id 1174781BC; Mon, 8 May 2023 08:20:32 +0000 (UTC) From: Tony Lindgren To: Greg Kroah-Hartman , Jiri Slaby Cc: Andy Shevchenko , Dhruva Gole , =?utf-8?q?Ilpo_J=C3=A4rvinen?= , Johan Hovold , Sebastian Andrzej Siewior , Vignesh Raghavendra , linux-omap@vger.kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/4] serial: 8250: omap: Fix imprecise external abort for omap_8250_pm() Date: Mon, 8 May 2023 11:20:12 +0300 Message-Id: <20230508082014.23083-3-tony@atomide.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230508082014.23083-1-tony@atomide.com> References: <20230508082014.23083-1-tony@atomide.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org We must idle the uart only after serial8250_unregister_port(). Otherwise unbinding the uart via sysfs while doing cat on the port produces an imprecise external abort: mem_serial_in from omap_8250_pm+0x44/0xf4 omap_8250_pm from uart_hangup+0xe0/0x194 uart_hangup from __tty_hangup.part.0+0x37c/0x3a8 __tty_hangup.part.0 from uart_remove_one_port+0x9c/0x22c uart_remove_one_port from serial8250_unregister_port+0x60/0xe8 serial8250_unregister_port from omap8250_remove+0x6c/0xd0 omap8250_remove from platform_remove+0x28/0x54 Turns out the driver needs to have runtime PM functional before the driver probe calls serial8250_register_8250_port(). And it needs runtime PM after driver remove calls serial8250_unregister_port(). On probe, we need to read registers before registering the port in omap_serial_fill_features_erratas(). We do that with custom uart_read() already. On remove, after serial8250_unregister_port(), we need to write to the uart registers to idle the device. Let's add a custom uart_write() for that. Currently the uart register access depends on port->membase to be initialized, which won't work after serial8250_unregister_port(). Let's use priv->membase instead, and use it for runtime PM related functions to remove the dependency to port->membase for early and late register access. Note that during use, we need to check for a valid port in the runtime PM related functions. This is needed for the optional wakeup configuration. We now need to set the drvdata a bit earlier so it's available for the runtime PM functions. With the port checks in runtime PM functions, the old checks for priv in omap8250_runtime_suspend() and omap8250_runtime_resume() functions are no longer needed and are removed. Signed-off-by: Tony Lindgren --- drivers/tty/serial/8250/8250_omap.c | 70 ++++++++++++++++------------- 1 file changed, 38 insertions(+), 32 deletions(-) diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -32,6 +32,7 @@ #include "8250.h" #define DEFAULT_CLK_SPEED 48000000 +#define OMAP_UART_REGSHIFT 2 #define UART_ERRATA_i202_MDR1_ACCESS (1 << 0) #define OMAP_UART_WER_HAS_TX_WAKEUP (1 << 1) @@ -115,6 +116,7 @@ #define UART_OMAP_RX_LVL 0x19 struct omap8250_priv { + void __iomem *membase; int line; u8 habit; u8 mdr1; @@ -159,9 +161,14 @@ static void omap_8250_rx_dma_flush(struct uart_8250_port *p); static inline void omap_8250_rx_dma_flush(struct uart_8250_port *p) { } #endif -static u32 uart_read(struct uart_8250_port *up, u32 reg) +static u32 uart_read(struct omap8250_priv *priv, u32 reg) { - return readl(up->port.membase + (reg << up->port.regshift)); + return readl(priv->membase + (reg << OMAP_UART_REGSHIFT)); +} + +static void uart_write(struct omap8250_priv *priv, u32 reg, u32 val) +{ + writel(val, priv->membase + (reg << OMAP_UART_REGSHIFT)); } /* @@ -548,7 +555,7 @@ static void omap_serial_fill_features_erratas(struct uart_8250_port *up, u32 mvr, scheme; u16 revision, major, minor; - mvr = uart_read(up, UART_OMAP_MVER); + mvr = uart_read(priv, UART_OMAP_MVER); /* Check revision register scheme */ scheme = mvr >> OMAP_UART_MVR_SCHEME_SHIFT; @@ -1394,7 +1401,7 @@ static int omap8250_probe(struct platform_device *pdev) UPF_HARD_FLOW; up.port.private_data = priv; - up.port.regshift = 2; + up.port.regshift = OMAP_UART_REGSHIFT; up.port.fifosize = 64; up.tx_loadsz = 64; up.capabilities = UART_CAP_FIFO; @@ -1457,6 +1464,8 @@ static int omap8250_probe(struct platform_device *pdev) DEFAULT_CLK_SPEED); } + priv->membase = membase; + priv->line = -ENODEV; priv->latency = PM_QOS_CPU_LATENCY_DEFAULT_VALUE; priv->calc_latency = PM_QOS_CPU_LATENCY_DEFAULT_VALUE; cpu_latency_qos_add_request(&priv->pm_qos_request, priv->latency); @@ -1464,6 +1473,8 @@ static int omap8250_probe(struct platform_device *pdev) spin_lock_init(&priv->rx_dma_lock); + platform_set_drvdata(pdev, priv); + device_init_wakeup(&pdev->dev, true); pm_runtime_enable(&pdev->dev); pm_runtime_use_autosuspend(&pdev->dev); @@ -1525,7 +1536,6 @@ static int omap8250_probe(struct platform_device *pdev) goto err; } priv->line = ret; - platform_set_drvdata(pdev, priv); pm_runtime_mark_last_busy(&pdev->dev); pm_runtime_put_autosuspend(&pdev->dev); return 0; @@ -1547,11 +1557,12 @@ static int omap8250_remove(struct platform_device *pdev) if (err) return err; + serial8250_unregister_port(priv->line); + priv->line = -ENODEV; pm_runtime_dont_use_autosuspend(&pdev->dev); pm_runtime_put_sync(&pdev->dev); flush_work(&priv->qos_work); pm_runtime_disable(&pdev->dev); - serial8250_unregister_port(priv->line); cpu_latency_qos_remove_request(&priv->pm_qos_request); device_init_wakeup(&pdev->dev, false); return 0; @@ -1627,7 +1638,6 @@ static int omap8250_lost_context(struct uart_8250_port *up) static int omap8250_soft_reset(struct device *dev) { struct omap8250_priv *priv = dev_get_drvdata(dev); - struct uart_8250_port *up = serial8250_get_port(priv->line); int timeout = 100; int sysc; int syss; @@ -1641,20 +1651,20 @@ static int omap8250_soft_reset(struct device *dev) * needing omap8250_soft_reset() quirk. Do it in two writes as * recommended in the comment for omap8250_update_scr(). */ - serial_out(up, UART_OMAP_SCR, OMAP_UART_SCR_DMAMODE_1); - serial_out(up, UART_OMAP_SCR, + uart_write(priv, UART_OMAP_SCR, OMAP_UART_SCR_DMAMODE_1); + uart_write(priv, UART_OMAP_SCR, OMAP_UART_SCR_DMAMODE_1 | OMAP_UART_SCR_DMAMODE_CTL); - sysc = serial_in(up, UART_OMAP_SYSC); + sysc = uart_read(priv, UART_OMAP_SYSC); /* softreset the UART */ sysc |= OMAP_UART_SYSC_SOFTRESET; - serial_out(up, UART_OMAP_SYSC, sysc); + uart_write(priv, UART_OMAP_SYSC, sysc); /* By experiments, 1us enough for reset complete on AM335x */ do { udelay(1); - syss = serial_in(up, UART_OMAP_SYSS); + syss = uart_read(priv, UART_OMAP_SYSS); } while (--timeout && !(syss & OMAP_UART_SYSS_RESETDONE)); if (!timeout) { @@ -1668,13 +1678,10 @@ static int omap8250_soft_reset(struct device *dev) static int omap8250_runtime_suspend(struct device *dev) { struct omap8250_priv *priv = dev_get_drvdata(dev); - struct uart_8250_port *up; + struct uart_8250_port *up = NULL; - /* In case runtime-pm tries this before we are setup */ - if (!priv) - return 0; - - up = serial8250_get_port(priv->line); + if (priv->line >= 0) + up = serial8250_get_port(priv->line); /* * When using 'no_console_suspend', the console UART must not be * suspended. Since driver suspend is managed by runtime suspend, @@ -1682,7 +1689,7 @@ static int omap8250_runtime_suspend(struct device *dev) * active during suspend. */ if (priv->is_suspending && !console_suspend_enabled) { - if (uart_console(&up->port)) + if (up && uart_console(&up->port)) return -EBUSY; } @@ -1693,13 +1700,15 @@ static int omap8250_runtime_suspend(struct device *dev) if (ret) return ret; - /* Restore to UART mode after reset (for wakeup) */ - omap8250_update_mdr1(up, priv); - /* Restore wakeup enable register */ - serial_out(up, UART_OMAP_WER, priv->wer); + if (up) { + /* Restore to UART mode after reset (for wakeup) */ + omap8250_update_mdr1(up, priv); + /* Restore wakeup enable register */ + serial_out(up, UART_OMAP_WER, priv->wer); + } } - if (up->dma && up->dma->rxchan) + if (up && up->dma && up->dma->rxchan) omap_8250_rx_dma_flush(up); priv->latency = PM_QOS_CPU_LATENCY_DEFAULT_VALUE; @@ -1711,18 +1720,15 @@ static int omap8250_runtime_suspend(struct device *dev) static int omap8250_runtime_resume(struct device *dev) { struct omap8250_priv *priv = dev_get_drvdata(dev); - struct uart_8250_port *up; + struct uart_8250_port *up = NULL; - /* In case runtime-pm tries this before we are setup */ - if (!priv) - return 0; + if (priv->line >= 0) + up = serial8250_get_port(priv->line); - up = serial8250_get_port(priv->line); - - if (omap8250_lost_context(up)) + if (up && omap8250_lost_context(up)) omap8250_restore_regs(up); - if (up->dma && up->dma->rxchan && !(priv->habit & UART_HAS_EFR2)) + if (up && up->dma && up->dma->rxchan && !(priv->habit & UART_HAS_EFR2)) omap_8250_rx_dma(up); priv->latency = priv->calc_latency;