On 01/16/2017 08:30 AM, Bartosz Golaszewski wrote:
2017-01-16 13:45 GMT+01:00 Sekhar Nori <nsekhar@xxxxxx>:
On Monday 16 January 2017 03:43 PM, Bartosz Golaszewski wrote:
2017-01-13 20:25 GMT+01:00 David Lechner <david@xxxxxxxxxxxxxx>:
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.
[1]: https://github.com/dlech/ev3dev-kernel/commits/wip-20160509
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.c
b/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.c
b/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 clock
failed: %d",
+ __func__, ret);
+ }
+
of_platform_default_populate(NULL, da850_auxdata_lookup, NULL);
davinci_pm_init();
pdata_quirks_init();
---
--
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