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Message-ID: <53AB4F2D.2060208@wwwdotorg.org>
Date: Wed, 25 Jun 2014 16:37:33 -0600
From: Stephen Warren <swarren@...dotorg.org>
To: Andrew Bresticker <abrestic@...omium.org>,
devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-usb@...r.kernel.org
CC: Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
Mark Rutland <mark.rutland@....com>,
Ian Campbell <ijc+devicetree@...lion.org.uk>,
Kumar Gala <galak@...eaurora.org>,
Randy Dunlap <rdunlap@...radead.org>,
Thierry Reding <thierry.reding@...il.com>,
Russell King <linux@....linux.org.uk>,
Linus Walleij <linus.walleij@...aro.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Mathias Nyman <mathias.nyman@...el.com>,
Grant Likely <grant.likely@...aro.org>,
Alan Stern <stern@...land.harvard.edu>,
Kishon Vijay Abraham I <kishon@...com>,
Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH v1 6/9] usb: xhci: Add NVIDIA Tegra XHCI host-controller
driver
On 06/18/2014 12:16 AM, Andrew Bresticker wrote:
> Add support for the on-chip XHCI host controller present on Tegra SoCs.
>
> The driver is currently very basic: it loads the controller with its
> firmware, starts the controller, and is able to service messages sent
> by the controller's firmware. The hardware supports device mode as
> well as runtime power-gating, but support for these is not yet
> implemented here.
>
> Based on work by:
> Ajay Gupta <ajayg@...dia.com>
> Bharath Yadav <byadav@...dia.com>
> diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
> +config USB_XHCI_TEGRA
> + tristate "NVIDIA Tegra XHCI support"
> + depends on ARCH_TEGRA
> + select PINCTRL_TEGRA_XUSB
> + select TEGRA_XUSB_MBOX
> + select FW_LOADER
I think at least some of those should be depends. In particular, the
mbox driver patch said:
+config TEGRA_XUSB_MBOX
+ bool "NVIDIA Tegra XUSB mailbox support"
which means the option is user-selectable. Either MBOX should be
invisible and selected here, or it should be visible with USB_XHCI_TEGRA
depending on it.
> diff --git a/drivers/usb/host/xhci-tegra.c b/drivers/usb/host/xhci-tegra.c
> +#define TEGRA_XHCI_UTMI_PHYS 3
> +#define TEGRA_XHCI_HSIC_PHYS 2
> +#define TEGRA_XHCI_USB3_PHYS 2
> +#define TEGRA_XHCI_MAX_PHYS (TEGRA_XHCI_UTMI_PHYS + TEGRA_XHCI_HSIC_PHYS + \
> + TEGRA_XHCI_USB3_PHYS)
Do those numbers need to be synchronized with the XUSB padctrl driver at
all?
> +static u32 csb_readl(struct tegra_xhci_hcd *tegra, u32 addr)
> +{
> + u32 page, offset;
> +
> + page = CSB_PAGE_SELECT(addr);
> + offset = CSB_PAGE_OFFSET(addr);
> + fpci_writel(tegra, page, XUSB_CFG_ARU_C11_CSBRANGE);
> + return fpci_readl(tegra, XUSB_CFG_CSB_BASE_ADDR + offset);
> +}
I assume some higher level has the required locking or single-threading
so that the keyhole register accesses don't get interleaved?
> +static void tegra_xhci_cfg(struct tegra_xhci_hcd *tegra)
> +{
> + u32 reg;
> +
> + reg = ipfs_readl(tegra, IPFS_XUSB_HOST_CONFIGURATION_0);
> + reg |= IPFS_EN_FPCI;
> + ipfs_writel(tegra, reg, IPFS_XUSB_HOST_CONFIGURATION_0);
> + udelay(10);
> +
> + /* Program Bar0 Space */
> + reg = fpci_readl(tegra, XUSB_CFG_4);
> + reg |= tegra->hcd->rsrc_start;
Don't you need to mask out the original value here? I guess whatever is
being written is probably always the same, but it seems scary to assume
that a bootloader, or previous version of a module during development,
didn't write something unexpected there. Perhaps if the HW module's
reset is pulsed we don't need to worry though.
> +static int tegra_xhci_load_firmware(struct tegra_xhci_hcd *tegra)
> +{
> + struct device *dev = tegra->dev;
> + struct tegra_xhci_fw_cfgtbl *cfg_tbl;
> + u64 fw_base;
> + u32 val;
> + time_t fw_time;
> + struct tm fw_tm;
> +
> + if (csb_readl(tegra, XUSB_CSB_MP_ILOAD_BASE_LO) != 0) {
> + dev_info(dev, "Firmware already loaded, Falcon state 0x%x\n",
> + csb_readl(tegra, XUSB_FALC_CPUCTL));
> + return 0;
> + }
> +
> + cfg_tbl = (struct tegra_xhci_fw_cfgtbl *)tegra->fw_data;
Are there endianness or CPU word size (e.g. ARMv8) issues here; this is
casting the content of a data file to a CPU data structure.
> +static int tegra_xhci_set_ss_clk(struct tegra_xhci_hcd *tegra,
> + unsigned long rate)
> + switch (rate) {
> + case TEGRA_XHCI_SS_CLK_HIGH_SPEED:
> + /* Reparent to PLLU_480M. Set div first to avoid overclocking */
> + old_parent_rate = clk_get_rate(clk_get_parent(clk));
> + new_parent_rate = clk_get_rate(tegra->pll_u_480m);
> + div = new_parent_rate / rate;
> + ret = clk_set_rate(clk, old_parent_rate / div);
> + if (ret)
> + return ret;
> + ret = clk_set_parent(clk, tegra->pll_u_480m);
> + if (ret)
> + return ret;
Don't you need to call clk_set_rate() again after reparenting, since the
divisor will be different, and the rounding too.
> +static int tegra_xhci_regulator_enable(struct tegra_xhci_hcd *tegra)
> +{
> + int ret;
> +
> + ret = regulator_enable(tegra->s3p3v_reg);
> + if (ret < 0)
> + return ret;
> + ret = regulator_enable(tegra->s1p8v_reg);
> + if (ret < 0)
> + goto disable_s3p3v;
> + ret = regulator_enable(tegra->s1p05v_reg);
> + if (ret < 0)
> + goto disable_s1p8v;
Would regulator_bulk_enable() save any code here? Similar in _disable().
> +static const struct tegra_xhci_soc_config tegra124_soc_config = {
> + .firmware_file = "tegra12x/tegra_xusb_firmware",
> +};
I would prefer an "nvidia/" prefix so everything gets namespaced by vendor.
"tegra12x" isn't the name of the chip, but rather "Tegra124".
"tegra_" and "_firmware" seem redundant, since they're implied by parent
directories.
So, how about "nvidia/tegra124/xusb"? (perhaps with .img or .bin file
extension)
> +static int tegra_xhci_probe(struct platform_device *pdev)
> + tegra->host_clk = devm_clk_get(&pdev->dev, "xusb_host");
> + if (IS_ERR(tegra->host_clk)) {
> + ret = PTR_ERR(tegra->host_clk);
> + goto put_hcd;
> + }
> + tegra->falc_clk = devm_clk_get(&pdev->dev, "xusb_falcon_src");
> + if (IS_ERR(tegra->falc_clk)) {
> + ret = PTR_ERR(tegra->falc_clk);
> + goto put_hcd;
> + }
...
Seems like devm_clk_get_bulk() would be useful:-)
> + for (i = 0; i < TEGRA_XHCI_UTMI_PHYS; i++) {
> + char prop[sizeof("utmi-N")];
> +
> + sprintf(prop, "utmi-%d", i);
Since this loop is cut/paste 3 times just with the string
"utmi"/"hsic"/"usb3" being different, does it make sense to add an outer
loop over an array of strings instead of duplicating the loo?
> + ret = request_firmware_nowait(THIS_MODULE, true,
> + tegra->soc_config->firmware_file,
> + tegra->dev, GFP_KERNEL, tegra,
> + tegra_xhci_probe_finish);
I'm not familiar with that API. I assume the point is this works in allh
the following situations:
* Driver is built-in, probes before rootfs is available, firmware
eventually gets loaded a few seconds after rootfs is available.
* Driver is a module and gets loaded from an initrd, firmware is loaded
from initrd essentially immediately.
* Driver is a module and gets loaded from an initrd, firmware eventually
gets loaded a few seconds after rootfs is available.
* Driver is a module and gets loaded from rootfs, firmware is loaded
from rootfs essentially immediately.
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