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usb: dwc3: reference clock period configuration

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Set reference clock period when it differs from dwc3 default hardware
set.

We could calculate clock period based on reference clock frequency. But
this information is not always available. This is the case of PCI bus
attached USB host. For that reason we use a custom property.

Tested (USB2 only) on IPQ6010 SoC based board with 24 MHz reference
clock while hardware default is 19.2 MHz.

[ baruch: rewrite commit message; drop GFLADJ code; remove 'quirk-' from
  property name; mention tested hardware ]

[ marek: Ported from Linux kernel commit
         7bee318838890 ("usb: dwc3: reference clock period configuration") ]

Reviewed-by: Sean Anderson <seanga2@gmail.com>
Signed-off-by: Balaji Prakash J <bjagadee@codeaurora.org>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Marek Vasut <marex@denx.de> # Port from Linux
This commit is contained in:
Balaji Prakash J 2022-11-27 15:31:53 +01:00 committed by Marek Vasut
parent 8ae84e6453
commit 57548e8bc7
2 changed files with 33 additions and 0 deletions
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27
drivers/usb/dwc3/core.c
View file

@ -28,6 +28,7 @@
#include <generic-phy.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/bitfield.h>
#include "core.h"
#include "gadget.h"
@ -114,6 +115,28 @@ static void dwc3_frame_length_adjustment(struct dwc3 *dwc, u32 fladj)
dwc3_writel(dwc->regs, DWC3_GFLADJ, reg);
}
/**
* dwc3_ref_clk_period - Reference clock period configuration
* Default reference clock period depends on hardware
* configuration. For systems with reference clock that differs
* from the default, this will set clock period in DWC3_GUCTL
* register.
* @dwc: Pointer to our controller context structure
* @ref_clk_per: reference clock period in ns
*/
static void dwc3_ref_clk_period(struct dwc3 *dwc)
{
u32 reg;
if (dwc->ref_clk_per == 0)
return;
reg = dwc3_readl(dwc->regs, DWC3_GUCTL);
reg &= ~DWC3_GUCTL_REFCLKPER_MASK;
reg |= FIELD_PREP(DWC3_GUCTL_REFCLKPER_MASK, dwc->ref_clk_per);
dwc3_writel(dwc->regs, DWC3_GUCTL, reg);
}
/**
* dwc3_free_one_event_buffer - Frees one event buffer
* @dwc: Pointer to our controller context structure
@ -640,6 +663,9 @@ static int dwc3_core_init(struct dwc3 *dwc)
/* Adjust Frame Length */
dwc3_frame_length_adjustment(dwc, dwc->fladj);
/* Adjust Reference Clock Period */
dwc3_ref_clk_period(dwc);
dwc3_set_incr_burst_type(dwc);
return 0;
@ -1043,6 +1069,7 @@ void dwc3_of_parse(struct dwc3 *dwc)
| (dwc->is_utmi_l1_suspend << 4);
dev_read_u32(dev, "snps,quirk-frame-length-adjustment", &dwc->fladj);
dev_read_u32(dev, "snps,ref-clock-period-ns", &dwc->ref_clk_per);
/*
* Handle property "snps,incr-burst-type-adjustment".

6
drivers/usb/dwc3/core.h
View file

@ -249,6 +249,10 @@
#define DWC3_GFLADJ_30MHZ_SDBND_SEL (1 << 7)
#define DWC3_GFLADJ_30MHZ_MASK 0x3f
/* Global User Control Register*/
#define DWC3_GUCTL_REFCLKPER_MASK 0xffc00000
#define DWC3_GUCTL_REFCLKPER_SEL 22
/* Device Configuration Register */
#define DWC3_DCFG_DEVADDR(addr) ((addr) << 3)
#define DWC3_DCFG_DEVADDR_MASK DWC3_DCFG_DEVADDR(0x7f)
@ -671,6 +675,7 @@ struct dwc3_scratchpad_array {
* @ref_clk: reference clock
* @regs: base address for our registers
* @regs_size: address space size
* @ref_clk_per: reference clock period configuration
* @nr_scratch: number of scratch buffers
* @num_event_buffers: calculated number of event buffers
* @u1u2: only used on revisions <1.83a for workaround
@ -832,6 +837,7 @@ struct dwc3 {
u8 lpm_nyet_threshold;
u8 hird_threshold;
u32 fladj;
u32 ref_clk_per;
u8 incrx_mode;
u32 incrx_size;