931db7d688
Patch from Lennert Buytenhek The workaround that we do for avoiding triggering ixp2400 erratum #66 involves mapping I/O pages using XCB=101 instead of XCB=000 so that we prevent the I/O signal to the gasket from being asserted (which can cause data corruption.) But XCB=101 mappings are write-buffered while mappings using XCB=000 are not, which is why if we use XCB=101 mappings we do a readback for every CSR store in an attempt to make sure that the store has been pushed out of the xscale core and the gasket. Unfortunately, there are two issues with this: - we do a readback for every CSR store, which is wrong, because the register we are writing to might have unwanted side-effects on read, for example, in the case of the scratchpad ring enqueue/dequeue registers; and - the readback is totally ineffective in the way we currently do it, because we just issue a load but do not issue any instruction that depends on the return value of that load, so the xscale core does not wait for the load to complete before continuing. See this linux-arm-kernel mailing list post for further information: http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2005-September/031314.html This means that my ixp2400 boxes have been running for many months without a working readback in ixp2000_reg_write, without any apparent adverse effects. Two of them have been running for a week now with the actual readback deleted from ixp2000_reg_write, also without any apparent ill effects. So, because in its current form it does more harm than good, the readback in ixp2000_reg_write should simply be killed, as the patch below does. Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org> Signed-off-by: Deepak Saxena <dsaxena@plexity.net> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
123 lines
3.7 KiB
C
123 lines
3.7 KiB
C
/*
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* include/asm-arm/arch-ixp2000/platform.h
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*
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* Various bits of code used by platform-level code.
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*
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* Author: Deepak Saxena <dsaxena@plexity.net>
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*
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* Copyright 2004 (c) MontaVista Software, Inc.
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*/
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#ifndef __ASSEMBLY__
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static inline void ixp2000_reg_write(volatile void *reg, unsigned long val)
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{
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*((volatile unsigned long *)reg) = val;
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}
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#define ixp2000_reg_read(reg) (*((volatile unsigned long *)reg))
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/*
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* Boards may multiplex different devices on the 2nd channel of
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* the slowport interface that each need different configuration
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* settings. For example, the IXDP2400 uses channel 2 on the interface
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* to access the CPLD, the switch fabric card, and the media card. Each
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* one needs a different mode so drivers must save/restore the mode
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* before and after each operation.
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*
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* acquire_slowport(&your_config);
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* ...
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* do slowport operations
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* ...
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* release_slowport();
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*
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* Note that while you have the slowport, you are holding a spinlock,
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* so your code should be written as if you explicitly acquired a lock.
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*
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* The configuration only affects device 2 on the slowport, so the
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* MTD map driver does not acquire/release the slowport.
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*/
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struct slowport_cfg {
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unsigned long CCR; /* Clock divide */
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unsigned long WTC; /* Write Timing Control */
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unsigned long RTC; /* Read Timing Control */
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unsigned long PCR; /* Protocol Control Register */
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unsigned long ADC; /* Address/Data Width Control */
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};
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void ixp2000_acquire_slowport(struct slowport_cfg *, struct slowport_cfg *);
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void ixp2000_release_slowport(struct slowport_cfg *);
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/*
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* IXP2400 A0/A1 and IXP2800 A0/A1/A2 have broken slowport that requires
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* tweaking of addresses in the MTD driver.
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*/
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static inline unsigned ixp2000_has_broken_slowport(void)
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{
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unsigned long id = *IXP2000_PRODUCT_ID;
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unsigned long id_prod = id & (IXP2000_MAJ_PROD_TYPE_MASK |
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IXP2000_MIN_PROD_TYPE_MASK);
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return (((id_prod ==
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/* fixed in IXP2400-B0 */
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(IXP2000_MAJ_PROD_TYPE_IXP2000 |
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IXP2000_MIN_PROD_TYPE_IXP2400)) &&
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((id & IXP2000_MAJ_REV_MASK) == 0)) ||
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((id_prod ==
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/* fixed in IXP2800-B0 */
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(IXP2000_MAJ_PROD_TYPE_IXP2000 |
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IXP2000_MIN_PROD_TYPE_IXP2800)) &&
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((id & IXP2000_MAJ_REV_MASK) == 0)) ||
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((id_prod ==
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/* fixed in IXP2850-B0 */
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(IXP2000_MAJ_PROD_TYPE_IXP2000 |
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IXP2000_MIN_PROD_TYPE_IXP2850)) &&
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((id & IXP2000_MAJ_REV_MASK) == 0)));
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}
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static inline unsigned int ixp2000_has_flash(void)
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{
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return ((*IXP2000_STRAP_OPTIONS) & (CFG_BOOT_PROM));
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}
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static inline unsigned int ixp2000_is_pcimaster(void)
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{
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return ((*IXP2000_STRAP_OPTIONS) & (CFG_PCI_BOOT_HOST));
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}
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void ixp2000_map_io(void);
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void ixp2000_uart_init(void);
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void ixp2000_init_irq(void);
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void ixp2000_init_time(unsigned long);
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unsigned long ixp2000_gettimeoffset(void);
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struct pci_sys_data;
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u32 *ixp2000_pci_config_addr(unsigned int bus, unsigned int devfn, int where);
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void ixp2000_pci_preinit(void);
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int ixp2000_pci_setup(int, struct pci_sys_data*);
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struct pci_bus* ixp2000_pci_scan_bus(int, struct pci_sys_data*);
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int ixp2000_pci_read_config(struct pci_bus*, unsigned int, int, int, u32 *);
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int ixp2000_pci_write_config(struct pci_bus*, unsigned int, int, int, u32);
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/*
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* Several of the IXP2000 systems have banked flash so we need to extend the
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* flash_platform_data structure with some private pointers
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*/
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struct ixp2000_flash_data {
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struct flash_platform_data *platform_data;
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int nr_banks;
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unsigned long (*bank_setup)(unsigned long);
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};
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struct ixp2000_i2c_pins {
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unsigned long sda_pin;
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unsigned long scl_pin;
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};
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#endif /* !__ASSEMBLY__ */
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