Hi Marc, > -----Original Message----- > From: Marc Kleine-Budde [mailto:m...@pengutronix.de] > Sent: 2015年11月18日 18:23 > To: Yang, Wenyou; Wolfgang Grandegger > Cc: linux-...@vger.kernel.org; net...@vger.kernel.org; linux- > ker...@vger.kernel.org; Ferre, Nicolas > Subject: Re: [PATCH 2/2] can: m_can: Add CAN clock generated by UPLLCK > support > > On 11/18/2015 11:04 AM, Wenyou Yang wrote: > > As said SAMA5D2 datasheet, it is recommended to use the CAN clock at > > frequencies of 20, 40 or 80 MHz. To achieve these frequencies, PMC > > GCK3 must select the UPLLCK(480 MHz) as source clock and divide by 24, > > 12 or 6. In this patch the CAN clock at 20 MHz. > > > > As it is configured through DT, it doesn't affect the M_CAN without > > configuring CAN clock and its generated clock. > > > > Signed-off-by: Wenyou Yang <wenyou.y...@atmel.com> > > NACK > > Please do this setup in your SoC code, where you setup the clock > infrastructure or > have a look at Documentation/devicetree/bindings/clock/clock-bindings.txt > "Assigned clock parents and rates" Thank you for your advice. I will do this setup via DT.
> > > --- > > > > drivers/net/can/m_can/m_can.c | 16 +++++++++++++++- > > 1 file changed, 15 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/net/can/m_can/m_can.c > > b/drivers/net/can/m_can/m_can.c index fd1caa0..2ca47db 100644 > > --- a/drivers/net/can/m_can/m_can.c > > +++ b/drivers/net/can/m_can/m_can.c > > @@ -269,6 +269,8 @@ enum m_can_mram_cfg { > > #define TX_BUF_XTD BIT(30) > > #define TX_BUF_RTR BIT(29) > > > > +#define AT91_CAN_CLK_FREQ 20000000 > > + > > /* address offset and element number for each FIFO/Buffer in the > > Message RAM */ struct mram_cfg { > > u16 off; > > @@ -1188,7 +1190,7 @@ static int m_can_plat_probe(struct platform_device > *pdev) > > struct m_can_priv *priv; > > struct resource *res; > > void __iomem *addr; > > - struct clk *hclk, *cclk; > > + struct clk *hclk, *cclk, *upll_clk; > > int irq, ret; > > > > hclk = devm_clk_get(&pdev->dev, "hclk"); @@ -1198,6 +1200,18 @@ > > static int m_can_plat_probe(struct platform_device *pdev) > > return -ENODEV; > > } > > > > + upll_clk = devm_clk_get(&pdev->dev, "upllclk"); > > + if (!IS_ERR(upll_clk)) { > > + ret = clk_set_parent(cclk, upll_clk); > > + if (!ret) { > > + ret = clk_set_rate(cclk, AT91_CAN_CLK_FREQ); > > + if (ret) { > > + dev_err(&pdev->dev, "failed to set gck\n"); > > + return -ENODEV; > > + } > > + } > > + } > > + > > res = platform_get_resource_byname(pdev, IORESOURCE_MEM, > "m_can"); > > addr = devm_ioremap_resource(&pdev->dev, res); > > irq = platform_get_irq_byname(pdev, "int0"); > > > > regards, > Marc > > -- > Pengutronix e.K. | Marc Kleine-Budde | > Industrial Linux Solutions | Phone: +49-231-2826-924 | > Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | > Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de | Best Regards, Wenyou Yang