From 9b00b300e7bce032c467c36ca47fe2a776887fc2 Mon Sep 17 00:00:00 2001 From: Marc Kleine-Budde Date: Fri, 28 Feb 2014 15:30:18 +0100 Subject: [PATCH] can: flexcan: fix transition from and to low power mode in chip_{en,dis}able In flexcan_chip_enable() and flexcan_chip_disable() fixed delays are used. Experiments have shown that the transition from and to low power mode may take several microseconds. This patch adds a while loop which polls the Low Power Mode ACK bit (LPM_ACK) that indicates a successfull mode change. If the function runs into a timeout a error value is returned. Cc: linux-stable Signed-off-by: Marc Kleine-Budde --- drivers/net/can/flexcan.c | 50 +++++++++++++++++++++++++++++---------- 1 file changed, 38 insertions(+), 12 deletions(-) diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c index 30af702a07ad..5af60ab23e6f 100644 --- a/drivers/net/can/flexcan.c +++ b/drivers/net/can/flexcan.c @@ -144,6 +144,8 @@ #define FLEXCAN_MB_CODE_MASK (0xf0ffffff) +#define FLEXCAN_TIMEOUT_US (50) + /* * FLEXCAN hardware feature flags * @@ -269,26 +271,42 @@ static inline int flexcan_has_and_handle_berr(const struct flexcan_priv *priv, (reg_esr & FLEXCAN_ESR_ERR_BUS); } -static inline void flexcan_chip_enable(struct flexcan_priv *priv) +static int flexcan_chip_enable(struct flexcan_priv *priv) { struct flexcan_regs __iomem *regs = priv->base; + unsigned int timeout = FLEXCAN_TIMEOUT_US / 10; u32 reg; reg = flexcan_read(®s->mcr); reg &= ~FLEXCAN_MCR_MDIS; flexcan_write(reg, ®s->mcr); - udelay(10); + while (timeout-- && (flexcan_read(®s->mcr) & FLEXCAN_MCR_LPM_ACK)) + usleep_range(10, 20); + + if (flexcan_read(®s->mcr) & FLEXCAN_MCR_LPM_ACK) + return -ETIMEDOUT; + + return 0; } -static inline void flexcan_chip_disable(struct flexcan_priv *priv) +static int flexcan_chip_disable(struct flexcan_priv *priv) { struct flexcan_regs __iomem *regs = priv->base; + unsigned int timeout = FLEXCAN_TIMEOUT_US / 10; u32 reg; reg = flexcan_read(®s->mcr); reg |= FLEXCAN_MCR_MDIS; flexcan_write(reg, ®s->mcr); + + while (timeout-- && !(flexcan_read(®s->mcr) & FLEXCAN_MCR_LPM_ACK)) + usleep_range(10, 20); + + if (!(flexcan_read(®s->mcr) & FLEXCAN_MCR_LPM_ACK)) + return -ETIMEDOUT; + + return 0; } static int flexcan_get_berr_counter(const struct net_device *dev, @@ -709,7 +727,9 @@ static int flexcan_chip_start(struct net_device *dev) u32 reg_mcr, reg_ctrl; /* enable module */ - flexcan_chip_enable(priv); + err = flexcan_chip_enable(priv); + if (err) + return err; /* soft reset */ flexcan_write(FLEXCAN_MCR_SOFTRST, ®s->mcr); @@ -949,12 +969,16 @@ static int register_flexcandev(struct net_device *dev) goto out_disable_ipg; /* select "bus clock", chip must be disabled */ - flexcan_chip_disable(priv); + err = flexcan_chip_disable(priv); + if (err) + goto out_disable_per; reg = flexcan_read(®s->ctrl); reg |= FLEXCAN_CTRL_CLK_SRC; flexcan_write(reg, ®s->ctrl); - flexcan_chip_enable(priv); + err = flexcan_chip_enable(priv); + if (err) + goto out_chip_disable; /* set freeze, halt and activate FIFO, restrict register access */ reg = flexcan_read(®s->mcr); @@ -971,14 +995,15 @@ static int register_flexcandev(struct net_device *dev) if (!(reg & FLEXCAN_MCR_FEN)) { netdev_err(dev, "Could not enable RX FIFO, unsupported core\n"); err = -ENODEV; - goto out_disable_per; + goto out_chip_disable; } err = register_candev(dev); - out_disable_per: /* disable core and turn off clocks */ + out_chip_disable: flexcan_chip_disable(priv); + out_disable_per: clk_disable_unprepare(priv->clk_per); out_disable_ipg: clk_disable_unprepare(priv->clk_ipg); @@ -1121,8 +1146,11 @@ static int flexcan_suspend(struct device *device) { struct net_device *dev = dev_get_drvdata(device); struct flexcan_priv *priv = netdev_priv(dev); + int err; - flexcan_chip_disable(priv); + err = flexcan_chip_disable(priv); + if (err) + return err; if (netif_running(dev)) { netif_stop_queue(dev); @@ -1143,9 +1171,7 @@ static int flexcan_resume(struct device *device) netif_device_attach(dev); netif_start_queue(dev); } - flexcan_chip_enable(priv); - - return 0; + return flexcan_chip_enable(priv); } #endif /* CONFIG_PM_SLEEP */ -- 2.39.2