91a687d8fe
The Tegra EHCI driver directly calls various functions in the Tegra USB
PHY driver. The reverse is also true; the PHY driver calls into the EHCI
driver. This is problematic when the two are built as modules.
The calls from the PHY to EHCI driver were originally added in commit
bbdabdb "usb: add APIs to access host registers from Tegra PHY", for the
following reasons:
1) The register being touched is an EHCI register, so logically only the
EHCI driver should touch it.
2) (1) implies that some locking may be needed to correctly implement the
r/m/w access to this shared register.
3) We were expecting to pass only the PHY register space to the Tegra PHY
driver, and hence it would not have access to touch the shared
registers.
To solve this, that commit added functions in the EHCI driver to touch the
shared register on behalf of the PHY driver.
In practice, we ended up not having any locking in the implementaiton of
those functions, and I've been led to believe this is safe. Equally, (3)
did not happen either. Hence, it is possible for the PHY driver to touch
the shared register directly.
Given that, this patch moves the code to touch the shared register back
into the PHY driver, to eliminate the module problems. If we actually
need locking or co-ordination in the future, I propose we put the lock
support into some pre-existing core module, or into a third separate
module, in order to avoid the circular dependencies.
I apologize for my contribution to code churn here.
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
79 lines
1.8 KiB
C
79 lines
1.8 KiB
C
/*
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* Copyright (C) 2010 Google, Inc.
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*
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* This software is licensed under the terms of the GNU General Public
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* License version 2, as published by the Free Software Foundation, and
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* may be copied, distributed, and modified under those terms.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#ifndef __TEGRA_USB_PHY_H
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#define __TEGRA_USB_PHY_H
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#include <linux/clk.h>
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#include <linux/usb/otg.h>
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struct tegra_utmip_config {
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u8 hssync_start_delay;
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u8 elastic_limit;
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u8 idle_wait_delay;
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u8 term_range_adj;
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u8 xcvr_setup;
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u8 xcvr_lsfslew;
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u8 xcvr_lsrslew;
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};
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struct tegra_ulpi_config {
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int reset_gpio;
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const char *clk;
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};
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enum tegra_usb_phy_port_speed {
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TEGRA_USB_PHY_PORT_SPEED_FULL = 0,
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TEGRA_USB_PHY_PORT_SPEED_LOW,
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TEGRA_USB_PHY_PORT_SPEED_HIGH,
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};
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enum tegra_usb_phy_mode {
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TEGRA_USB_PHY_MODE_DEVICE,
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TEGRA_USB_PHY_MODE_HOST,
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TEGRA_USB_PHY_MODE_OTG,
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};
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struct tegra_xtal_freq;
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struct tegra_usb_phy {
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int instance;
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const struct tegra_xtal_freq *freq;
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void __iomem *regs;
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void __iomem *pad_regs;
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struct clk *clk;
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struct clk *pll_u;
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struct clk *pad_clk;
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enum tegra_usb_phy_mode mode;
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void *config;
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struct usb_phy *ulpi;
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struct usb_phy u_phy;
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struct device *dev;
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bool is_legacy_phy;
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bool is_ulpi_phy;
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int reset_gpio;
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};
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struct usb_phy *tegra_usb_get_phy(struct device_node *dn);
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void tegra_usb_phy_preresume(struct usb_phy *phy);
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void tegra_usb_phy_postresume(struct usb_phy *phy);
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void tegra_ehci_phy_restore_start(struct usb_phy *phy,
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enum tegra_usb_phy_port_speed port_speed);
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void tegra_ehci_phy_restore_end(struct usb_phy *phy);
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#endif /* __TEGRA_USB_PHY_H */
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