Messages in this thread | | | Date | Mon, 24 Jan 2011 23:23:02 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH 2/4] arch/arm/mach-at91/clock.c: Add missing IS_ERR test |
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On Tue, Jan 25, 2011 at 10:51:38AM +1300, Ryan Mallon wrote: > You could, but it would not be helpful. Clock associations are used so > that _different_ devices can have the same function and map to the > correct clock. This is used when there are multiple instances of a > single peripheral. For example, the uart clocks work like this: > > at91_clock_associate("usart1_clk", &pdev->dev, "usart"); > > so then you can do this in a driver: > > uart_clk = clk_get(&pdev->dev, "usart"); > > Rather than: > > uart_clk = clk_get(NULL, "usart1_clk"); > > The former will find the correct uart clock for the device. Because each > uart is a separate device the correct clock will be selected for each uart. > > My point was that there should be no overlap between clk->name and > clk->function otherwise clk_get will not be able to return the correct > clock.
It would be nice if AT91 could switch over to using clkdev at some point, which greatly helps with associating struct clk's with their device/function names - and reduces the amount of "different" code.
You can then use clk_add_alias() to create aliases of an existing clock.
Looking at your clk_get(), I think one way to do this would be, in clk_register():
struct clk_lookup *cl;
/* create function-only entry */ cl = clkdev_alloc(clk, clk->name, NULL); if (!cl) return -ENOMEM; clkdev_add(cl);
/* not sure if you need this? */ if (clk->dev && clk->function) { cl = clkdev_alloc(clk, clk->function, "%s", dev_name(clk->dev)); if (!cl) return -ENOMEM; clkdev_add(cl); }
at91_clock_associate() becomes:
err = clk_add_alias(func, dev_name(dev), id, NULL); return err;
Although maybe in the long run see about removing at91_clock_associate() entirely as its just a wrapper.
The only requirement there is that 'dev' in each case is a registered device, otherwise dev_name() won't work.
You can then use the generic clk_get()/clk_put() which clkdev provides.
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