[PATCH 03/10] devicetree: bindings: add bindings for ahci-da850
From: Sekhar Nori <hidden>
Date: 2017-01-17 12:02:15
Also in:
linux-devicetree, linux-ide, lkml
On Tuesday 17 January 2017 12:17 AM, David Lechner wrote:
On 01/16/2017 08:30 AM, Bartosz Golaszewski wrote:quoted
2017-01-16 13:45 GMT+01:00 Sekhar Nori [off-list ref]:quoted
On Monday 16 January 2017 03:43 PM, Bartosz Golaszewski wrote:quoted
2017-01-13 20:25 GMT+01:00 David Lechner [off-list ref]:quoted
A clock multiplier property seems redundant if you are specifying a clock. It should be possible to get the rate from the clock to determine which multiplier is needed.I probably should have named it differently. This is not a multiplier of a clock derived from PLL0 or PLL1. Instead it's a value set by writing to the Port PHY Control Register (MPY bits) of the SATA controller that configures the multiplier for the external low-jitter clock. On the lcdk the signals (REFCLKP, REFCLKN) are provided by CDCM61001 (SATA OSCILLATOR component on the schematics). I'll find a better name and comment the property accordingly. FYI: the da850 platform does not use the common clock framework, so I don't specify the clock property on the sata node in the device tree. Instead I add the clock lookup entry in patch [01/10]. This is transparent for AHCI which can get the clock as usual by calling clk_get() in ahci_platform_get_resources().I think David's point is that the SATA_REFCLK needs to be modeled as a actual clock input to the IP. You should be able to get the rate using clk_get_rate() and make the MPY bits calculation depending on the incoming rate. You should be able to model the clock even when not using common clock framework. DA850 AHCI does not use a con_id at the moment (it assumes a single clock), and that needs to change.It's true that once davinci gets ported (is this planned?) to using the common clock framework, we could just create a fixed-clock node in da850-lcdk for the SATA oscillator, so the new property is redundant.I have some commits[1] where I started on converting da850 to use the common clock framework. But, I don't know anything about other davinci family devices, so I don't think I could really take that to completion without lots of help.
I can help with testing, reviewing and filling in any missing information. But I wont have time to write the code itself.
[1]: https://github.com/dlech/ev3dev-kernel/commits/wip-20160509
I see that you have made a copy of the keystone PSC driver. I think you will need pretty strong reasons to not use the same driver with some customization for DaVinci.
quoted hunk ↗ jump to hunk
quoted
What I don't get is how should I model a clock that is not configurable and is board-specific? Is hard-coding the relevant rate in da850.c with a huge FIXME the right way?In arch/arm/mach-davinci/usb-da8xx.c, there is a "usb_refclkin" that is very similar to the situation with the sata refclk. You could do something like this to register the clock... ---diff --git a/arch/arm/mach-davinci/devices-da8xx.cb/arch/arm/mach-davinci/devices-da8xx.c index c2457b3..790efce9 100644--- a/arch/arm/mach-davinci/devices-da8xx.c +++ b/arch/arm/mach-davinci/devices-da8xx.c@@ -1023,6 +1023,34 @@ int __init da8xx_register_spi_bus(int instance,unsigned num_chipselect) } #ifdef CONFIG_ARCH_DAVINCI_DA850 + +static struct clk sata_refclkin = { + .name = "sata_refclkin", + .set_rate = davinci_simple_set_rate, +}; + +static struct clk_lookup sata_refclkin_lookup = + CLK(NULL, "sata_refclkin", &sata_refclkin); + +/** + * da8xx_register_sata_refclkin - register SATA_REFCLKIN clock + * + * @rate: The clock rate in Hz + */ +int __init da850_register_sata_refclkin(int rate) +{ + int ret; + + sata_refclkin.rate = rate; + ret = clk_register(&sata_refclkin); + if (ret) + return ret; + + clkdev_add(&sata_refclkin_lookup); + + return 0; +} + static struct resource da850_sata_resources[] = { { .start = DA850_SATA_BASE,@@ -1055,8 +1083,11 @@ static struct platform_device da850_sata_device = { int __init da850_register_sata(unsigned long refclkpn) { - /* please see comment in drivers/ata/ahci_da850.c */ - BUG_ON(refclkpn != 100 * 1000 * 1000); + int err; + + err = da850_register_sata_refclkin(refclkpn); + if (err) + return err; return platform_device_register(&da850_sata_device); } ---Then to get things working from device tree, add this... ---diff --git a/arch/arm/mach-davinci/da8xx-dt.cb/arch/arm/mach-davinci/da8xx-dt.c index d2be194..b54bdd6 100644--- a/arch/arm/mach-davinci/da8xx-dt.c +++ b/arch/arm/mach-davinci/da8xx-dt.c@@ -60,6 +60,14 @@ static void __init da850_init_machine(void) pr_warn("%s: registering USB 1.1 PHY clock failed: %d", __func__, ret); + if (of_machine_is_compatible("ti,da850-evm") || + of_machine_is_compatible("ti,da850-lcdk")) { + ret = da850_register_sata_refclkin(100000000); + if (ret) + pr_warn("%s: registering SATA_REFCLK clockfailed: %d", + __func__, ret); + } + of_platform_default_populate(NULL, da850_auxdata_lookup, NULL); davinci_pm_init(); pdata_quirks_init();
This approach is fine. Thanks, Sekhar