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SubjectRe: [PATCH 2/2] can: m_can: Add CAN clock generated by UPLLCK support
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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.yang@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"

> ---
>
> 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 |
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