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linux/drivers/tty/serial/8250/8250_lpss.c
Andy Shevchenko d7dba6be0f dmaengine: dw: Remove misleading is_private property 
The commit a9ddb575d6

   ("dmaengine: dw_dmac: Enhance device tree support")

introduces is_private property in uncertain understanding what does it mean.

First of all, documentation defines DMA_PRIVATE capability as

Documentation/crypto/async-tx-api.txt:
  The DMA_PRIVATE capability flag is used to tag dma devices that should not be
  used by the general-purpose allocator. It can be set at initialization time
  if it is known that a channel will always be private. Alternatively,
  it is set when dma_request_channel() finds an unused "public" channel.

  A couple caveats to note when implementing a driver and consumer:
  1/ Once a channel has been privately allocated it will no longer be
     considered by the general-purpose allocator even after a call to
     dma_release_channel().
  2/ Since capabilities are specified at the device level a dma_device with
     multiple channels will either have all channels public, or all channels
     private.

Documentation/driver-api/dmaengine/provider.rst:
  - DMA_PRIVATE
    The devices only supports slave transfers, and as such isn't available
    for async transfers.

The capability had been introduced by the commit 59b5ec2144

  ("dmaengine: introduce dma_request_channel and private channels")

and some code didn't changed from that times ever.

Taking into consideration above and the fact that on all known platforms
Synopsys DesignWare DMA engine is attached to serve slave transfers,
the DMA_PRIVATE capability must be enabled for this device unconditionally.
Otherwise, as rightfully noticed in drivers/dma/at_xdmac.c:
  /*
   * Without DMA_PRIVATE the driver is not able to allocate more than
   * one channel, second allocation fails in private_candidate.
   */
because of of a caveats mentioned in above documentation excerpts.

So, remove conditional around DMA_PRIVATE followed by removal leftovers.

If someone wonders, DMA_PRIVATE can be not used if and only if the all channels
of the DMA controller are supposed to serve memory-to-memory like operations.
For example, EP93xx has two controllers, one of which can only perform
memory-to-memory transfers

Note, this change doesn't affect dmatest to be able to test such controllers.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (maintainer:SERIAL DRIVERS)
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
2019-01-07 17:57:13 +05:30

377 lines
9.0 KiB
C
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// SPDX-License-Identifier: GPL-2.0
/*
* 8250_lpss.c - Driver for UART on Intel Braswell and various other Intel SoCs
*
* Copyright (C) 2016 Intel Corporation
* Author: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
*/
#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/rational.h>
#include <linux/dmaengine.h>
#include <linux/dma/dw.h>
#include "8250.h"
#define PCI_DEVICE_ID_INTEL_QRK_UARTx 0x0936
#define PCI_DEVICE_ID_INTEL_BYT_UART1 0x0f0a
#define PCI_DEVICE_ID_INTEL_BYT_UART2 0x0f0c
#define PCI_DEVICE_ID_INTEL_BSW_UART1 0x228a
#define PCI_DEVICE_ID_INTEL_BSW_UART2 0x228c
#define PCI_DEVICE_ID_INTEL_BDW_UART1 0x9ce3
#define PCI_DEVICE_ID_INTEL_BDW_UART2 0x9ce4
/* Intel LPSS specific registers */
#define BYT_PRV_CLK 0x800
#define BYT_PRV_CLK_EN BIT(0)
#define BYT_PRV_CLK_M_VAL_SHIFT 1
#define BYT_PRV_CLK_N_VAL_SHIFT 16
#define BYT_PRV_CLK_UPDATE BIT(31)
#define BYT_TX_OVF_INT 0x820
#define BYT_TX_OVF_INT_MASK BIT(1)
struct lpss8250;
struct lpss8250_board {
unsigned long freq;
unsigned int base_baud;
int (*setup)(struct lpss8250 *, struct uart_port *p);
void (*exit)(struct lpss8250 *);
};
struct lpss8250 {
int line;
struct lpss8250_board *board;
/* DMA parameters */
struct uart_8250_dma dma;
struct dw_dma_chip dma_chip;
struct dw_dma_slave dma_param;
u8 dma_maxburst;
};
static void byt_set_termios(struct uart_port *p, struct ktermios *termios,
struct ktermios *old)
{
unsigned int baud = tty_termios_baud_rate(termios);
struct lpss8250 *lpss = p->private_data;
unsigned long fref = lpss->board->freq, fuart = baud * 16;
unsigned long w = BIT(15) - 1;
unsigned long m, n;
u32 reg;
/* Gracefully handle the B0 case: fall back to B9600 */
fuart = fuart ? fuart : 9600 * 16;
/* Get Fuart closer to Fref */
fuart *= rounddown_pow_of_two(fref / fuart);
/*
* For baud rates 0.5M, 1M, 1.5M, 2M, 2.5M, 3M, 3.5M and 4M the
* dividers must be adjusted.
*
* uartclk = (m / n) * 100 MHz, where m <= n
*/
rational_best_approximation(fuart, fref, w, w, &m, &n);
p->uartclk = fuart;
/* Reset the clock */
reg = (m << BYT_PRV_CLK_M_VAL_SHIFT) | (n << BYT_PRV_CLK_N_VAL_SHIFT);
writel(reg, p->membase + BYT_PRV_CLK);
reg |= BYT_PRV_CLK_EN | BYT_PRV_CLK_UPDATE;
writel(reg, p->membase + BYT_PRV_CLK);
p->status &= ~UPSTAT_AUTOCTS;
if (termios->c_cflag & CRTSCTS)
p->status |= UPSTAT_AUTOCTS;
serial8250_do_set_termios(p, termios, old);
}
static unsigned int byt_get_mctrl(struct uart_port *port)
{
unsigned int ret = serial8250_do_get_mctrl(port);
/* Force DCD and DSR signals to permanently be reported as active */
ret |= TIOCM_CAR | TIOCM_DSR;
return ret;
}
static int byt_serial_setup(struct lpss8250 *lpss, struct uart_port *port)
{
struct dw_dma_slave *param = &lpss->dma_param;
struct uart_8250_port *up = up_to_u8250p(port);
struct pci_dev *pdev = to_pci_dev(port->dev);
unsigned int dma_devfn = PCI_DEVFN(PCI_SLOT(pdev->devfn), 0);
struct pci_dev *dma_dev = pci_get_slot(pdev->bus, dma_devfn);
switch (pdev->device) {
case PCI_DEVICE_ID_INTEL_BYT_UART1:
case PCI_DEVICE_ID_INTEL_BSW_UART1:
case PCI_DEVICE_ID_INTEL_BDW_UART1:
param->src_id = 3;
param->dst_id = 2;
break;
case PCI_DEVICE_ID_INTEL_BYT_UART2:
case PCI_DEVICE_ID_INTEL_BSW_UART2:
case PCI_DEVICE_ID_INTEL_BDW_UART2:
param->src_id = 5;
param->dst_id = 4;
break;
default:
return -EINVAL;
}
param->dma_dev = &dma_dev->dev;
param->m_master = 0;
param->p_master = 1;
/* TODO: Detect FIFO size automaticaly for DesignWare 8250 */
port->fifosize = 64;
up->tx_loadsz = 64;
lpss->dma_maxburst = 16;
port->set_termios = byt_set_termios;
port->get_mctrl = byt_get_mctrl;
/* Disable TX counter interrupts */
writel(BYT_TX_OVF_INT_MASK, port->membase + BYT_TX_OVF_INT);
return 0;
}
#ifdef CONFIG_SERIAL_8250_DMA
static const struct dw_dma_platform_data qrk_serial_dma_pdata = {
.nr_channels = 2,
.chan_allocation_order = CHAN_ALLOCATION_ASCENDING,
.chan_priority = CHAN_PRIORITY_ASCENDING,
.block_size = 4095,
.nr_masters = 1,
.data_width = {4},
.multi_block = {0},
};
static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)
{
struct uart_8250_dma *dma = &lpss->dma;
struct dw_dma_chip *chip = &lpss->dma_chip;
struct dw_dma_slave *param = &lpss->dma_param;
struct pci_dev *pdev = to_pci_dev(port->dev);
int ret;
chip->dev = &pdev->dev;
chip->irq = pci_irq_vector(pdev, 0);
chip->regs = pci_ioremap_bar(pdev, 1);
chip->pdata = &qrk_serial_dma_pdata;
/* Falling back to PIO mode if DMA probing fails */
ret = dw_dma_probe(chip);
if (ret)
return;
pci_try_set_mwi(pdev);
/* Special DMA address for UART */
dma->rx_dma_addr = 0xfffff000;
dma->tx_dma_addr = 0xfffff000;
param->dma_dev = &pdev->dev;
param->src_id = 0;
param->dst_id = 1;
param->hs_polarity = true;
lpss->dma_maxburst = 8;
}
static void qrk_serial_exit_dma(struct lpss8250 *lpss)
{
struct dw_dma_slave *param = &lpss->dma_param;
if (!param->dma_dev)
return;
dw_dma_remove(&lpss->dma_chip);
}
#else /* CONFIG_SERIAL_8250_DMA */
static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port) {}
static void qrk_serial_exit_dma(struct lpss8250 *lpss) {}
#endif /* !CONFIG_SERIAL_8250_DMA */
static int qrk_serial_setup(struct lpss8250 *lpss, struct uart_port *port)
{
struct pci_dev *pdev = to_pci_dev(port->dev);
int ret;
pci_set_master(pdev);
ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
if (ret < 0)
return ret;
port->irq = pci_irq_vector(pdev, 0);
qrk_serial_setup_dma(lpss, port);
return 0;
}
static void qrk_serial_exit(struct lpss8250 *lpss)
{
qrk_serial_exit_dma(lpss);
}
static bool lpss8250_dma_filter(struct dma_chan *chan, void *param)
{
struct dw_dma_slave *dws = param;
if (dws->dma_dev != chan->device->dev)
return false;
chan->private = dws;
return true;
}
static int lpss8250_dma_setup(struct lpss8250 *lpss, struct uart_8250_port *port)
{
struct uart_8250_dma *dma = &lpss->dma;
struct dw_dma_slave *rx_param, *tx_param;
struct device *dev = port->port.dev;
if (!lpss->dma_param.dma_dev)
return 0;
rx_param = devm_kzalloc(dev, sizeof(*rx_param), GFP_KERNEL);
if (!rx_param)
return -ENOMEM;
tx_param = devm_kzalloc(dev, sizeof(*tx_param), GFP_KERNEL);
if (!tx_param)
return -ENOMEM;
*rx_param = lpss->dma_param;
dma->rxconf.src_maxburst = lpss->dma_maxburst;
*tx_param = lpss->dma_param;
dma->txconf.dst_maxburst = lpss->dma_maxburst;
dma->fn = lpss8250_dma_filter;
dma->rx_param = rx_param;
dma->tx_param = tx_param;
port->dma = dma;
return 0;
}
static int lpss8250_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
struct uart_8250_port uart;
struct lpss8250 *lpss;
int ret;
ret = pcim_enable_device(pdev);
if (ret)
return ret;
lpss = devm_kzalloc(&pdev->dev, sizeof(*lpss), GFP_KERNEL);
if (!lpss)
return -ENOMEM;
lpss->board = (struct lpss8250_board *)id->driver_data;
memset(&uart, 0, sizeof(struct uart_8250_port));
uart.port.dev = &pdev->dev;
uart.port.irq = pdev->irq;
uart.port.private_data = lpss;
uart.port.type = PORT_16550A;
uart.port.iotype = UPIO_MEM;
uart.port.regshift = 2;
uart.port.uartclk = lpss->board->base_baud * 16;
uart.port.flags = UPF_SHARE_IRQ | UPF_FIXED_PORT | UPF_FIXED_TYPE;
uart.capabilities = UART_CAP_FIFO | UART_CAP_AFE;
uart.port.mapbase = pci_resource_start(pdev, 0);
uart.port.membase = pcim_iomap(pdev, 0, 0);
if (!uart.port.membase)
return -ENOMEM;
ret = lpss->board->setup(lpss, &uart.port);
if (ret)
return ret;
ret = lpss8250_dma_setup(lpss, &uart);
if (ret)
goto err_exit;
ret = serial8250_register_8250_port(&uart);
if (ret < 0)
goto err_exit;
lpss->line = ret;
pci_set_drvdata(pdev, lpss);
return 0;
err_exit:
if (lpss->board->exit)
lpss->board->exit(lpss);
return ret;
}
static void lpss8250_remove(struct pci_dev *pdev)
{
struct lpss8250 *lpss = pci_get_drvdata(pdev);
serial8250_unregister_port(lpss->line);
if (lpss->board->exit)
lpss->board->exit(lpss);
}
static const struct lpss8250_board byt_board = {
.freq = 100000000,
.base_baud = 2764800,
.setup = byt_serial_setup,
};
static const struct lpss8250_board qrk_board = {
.freq = 44236800,
.base_baud = 2764800,
.setup = qrk_serial_setup,
.exit = qrk_serial_exit,
};
#define LPSS_DEVICE(id, board) { PCI_VDEVICE(INTEL, id), (kernel_ulong_t)&board }
static const struct pci_device_id pci_ids[] = {
LPSS_DEVICE(PCI_DEVICE_ID_INTEL_QRK_UARTx, qrk_board),
LPSS_DEVICE(PCI_DEVICE_ID_INTEL_BYT_UART1, byt_board),
LPSS_DEVICE(PCI_DEVICE_ID_INTEL_BYT_UART2, byt_board),
LPSS_DEVICE(PCI_DEVICE_ID_INTEL_BSW_UART1, byt_board),
LPSS_DEVICE(PCI_DEVICE_ID_INTEL_BSW_UART2, byt_board),
LPSS_DEVICE(PCI_DEVICE_ID_INTEL_BDW_UART1, byt_board),
LPSS_DEVICE(PCI_DEVICE_ID_INTEL_BDW_UART2, byt_board),
{ },
};
MODULE_DEVICE_TABLE(pci, pci_ids);
static struct pci_driver lpss8250_pci_driver = {
.name = "8250_lpss",
.id_table = pci_ids,
.probe = lpss8250_probe,
.remove = lpss8250_remove,
};
module_pci_driver(lpss8250_pci_driver);
MODULE_AUTHOR("Intel Corporation");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Intel LPSS UART driver");
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