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155 lines
3.9 KiB
155 lines
3.9 KiB
// SPDX-License-Identifier: GPL-2.0 |
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// LPC variant I/O for Microchip EC |
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// |
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// Copyright (C) 2016 Google, Inc |
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#include <linux/delay.h> |
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#include <linux/io.h> |
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#include <linux/mutex.h> |
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#include <linux/types.h> |
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#include "cros_ec_lpc_mec.h" |
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/* |
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* This mutex must be held while accessing the EMI unit. We can't rely on the |
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* EC mutex because memmap data may be accessed without it being held. |
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*/ |
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static struct mutex io_mutex; |
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static u16 mec_emi_base, mec_emi_end; |
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/** |
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* cros_ec_lpc_mec_emi_write_address() - Initialize EMI at a given address. |
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* |
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* @addr: Starting read / write address |
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* @access_type: Type of access, typically 32-bit auto-increment |
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*/ |
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static void cros_ec_lpc_mec_emi_write_address(u16 addr, |
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enum cros_ec_lpc_mec_emi_access_mode access_type) |
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{ |
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outb((addr & 0xfc) | access_type, MEC_EMI_EC_ADDRESS_B0(mec_emi_base)); |
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outb((addr >> 8) & 0x7f, MEC_EMI_EC_ADDRESS_B1(mec_emi_base)); |
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} |
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/** |
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* cros_ec_lpc_mec_in_range() - Determine if addresses are in MEC EMI range. |
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* |
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* @offset: Address offset |
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* @length: Number of bytes to check |
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* |
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* Return: 1 if in range, 0 if not, and -EINVAL on failure |
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* such as the mec range not being initialized |
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*/ |
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int cros_ec_lpc_mec_in_range(unsigned int offset, unsigned int length) |
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{ |
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if (length == 0) |
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return -EINVAL; |
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if (WARN_ON(mec_emi_base == 0 || mec_emi_end == 0)) |
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return -EINVAL; |
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if (offset >= mec_emi_base && offset < mec_emi_end) { |
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if (WARN_ON(offset + length - 1 >= mec_emi_end)) |
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return -EINVAL; |
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return 1; |
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} |
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if (WARN_ON(offset + length > mec_emi_base && offset < mec_emi_end)) |
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return -EINVAL; |
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return 0; |
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} |
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/** |
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* cros_ec_lpc_io_bytes_mec() - Read / write bytes to MEC EMI port. |
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* |
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* @io_type: MEC_IO_READ or MEC_IO_WRITE, depending on request |
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* @offset: Base read / write address |
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* @length: Number of bytes to read / write |
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* @buf: Destination / source buffer |
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* |
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* Return: 8-bit checksum of all bytes read / written |
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*/ |
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u8 cros_ec_lpc_io_bytes_mec(enum cros_ec_lpc_mec_io_type io_type, |
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unsigned int offset, unsigned int length, |
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u8 *buf) |
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{ |
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int i = 0; |
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int io_addr; |
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u8 sum = 0; |
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enum cros_ec_lpc_mec_emi_access_mode access, new_access; |
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/* Return checksum of 0 if window is not initialized */ |
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WARN_ON(mec_emi_base == 0 || mec_emi_end == 0); |
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if (mec_emi_base == 0 || mec_emi_end == 0) |
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return 0; |
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/* |
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* Long access cannot be used on misaligned data since reading B0 loads |
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* the data register and writing B3 flushes. |
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*/ |
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if (offset & 0x3 || length < 4) |
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access = ACCESS_TYPE_BYTE; |
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else |
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access = ACCESS_TYPE_LONG_AUTO_INCREMENT; |
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mutex_lock(&io_mutex); |
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/* Initialize I/O at desired address */ |
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cros_ec_lpc_mec_emi_write_address(offset, access); |
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/* Skip bytes in case of misaligned offset */ |
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io_addr = MEC_EMI_EC_DATA_B0(mec_emi_base) + (offset & 0x3); |
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while (i < length) { |
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while (io_addr <= MEC_EMI_EC_DATA_B3(mec_emi_base)) { |
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if (io_type == MEC_IO_READ) |
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buf[i] = inb(io_addr++); |
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else |
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outb(buf[i], io_addr++); |
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sum += buf[i++]; |
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offset++; |
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/* Extra bounds check in case of misaligned length */ |
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if (i == length) |
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goto done; |
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} |
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/* |
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* Use long auto-increment access except for misaligned write, |
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* since writing B3 triggers the flush. |
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*/ |
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if (length - i < 4 && io_type == MEC_IO_WRITE) |
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new_access = ACCESS_TYPE_BYTE; |
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else |
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new_access = ACCESS_TYPE_LONG_AUTO_INCREMENT; |
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if (new_access != access || |
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access != ACCESS_TYPE_LONG_AUTO_INCREMENT) { |
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access = new_access; |
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cros_ec_lpc_mec_emi_write_address(offset, access); |
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} |
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/* Access [B0, B3] on each loop pass */ |
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io_addr = MEC_EMI_EC_DATA_B0(mec_emi_base); |
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} |
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done: |
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mutex_unlock(&io_mutex); |
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return sum; |
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} |
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EXPORT_SYMBOL(cros_ec_lpc_io_bytes_mec); |
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void cros_ec_lpc_mec_init(unsigned int base, unsigned int end) |
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{ |
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mutex_init(&io_mutex); |
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mec_emi_base = base; |
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mec_emi_end = end; |
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} |
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EXPORT_SYMBOL(cros_ec_lpc_mec_init); |
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void cros_ec_lpc_mec_destroy(void) |
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{ |
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mutex_destroy(&io_mutex); |
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} |
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EXPORT_SYMBOL(cros_ec_lpc_mec_destroy);
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