[PATCH v2] can: flexcan: add 2nd clock to support imx53 and newer

[Hui Wang]

Marc Kleine-Budde wrote:
> From: Steffen Trumtrar <s.trumtrar at pengutronix.de>
>
> This patch adds support for a second clock to the flexcan driver. On
> modern freescale ARM cores like the imx53 and imx6q two clocks ("ipg"
> and "per") must be enabled in order to access the CAN core.
>
> In the original driver, the clock was requested without specifying the
> connection id, further all mainline ARM archs with flexcan support
> (imx28, imx25, imx35) register their flexcan clock without a
> connection id, too.
>
> This patch first renames the existing clk variable to clk_ipg and
> converts it to devm for easier error handling. The connection id "ipg"
> is added to the devm_clk_get() call. Then a second clock "per" is
> requested. As all archs don't specify a connection id, both clk_get
> return the same clock. This ensures compatibility to existing flexcan
> support and adds support for imx53 at the same time.
>
> After this patch hits mainline, the archs may give their existing
> flexcan clock the "ipg" connection id and implement a dummy "per"
> clock.
>
> This patch has been tested on imx28 (unmodified clk tree) and on imx53
> with a seperate "ipg" and "per" clock.
>
> Cc: Sascha Hauer <s.hauer at pengutronix.de>
> Cc: Shawn Guo <shawn.guo at linaro.org>
> Cc: Hui Wang <jason77.wang at gmail.com>
>   
Acked-by: Hui Wang <jason77.wang at gmail.com>