Messages in this thread | | | Date | Thu, 6 Oct 2022 14:47:40 -0700 (PDT) | From | matthew.gerlach@linux ... | Subject | Re: [PATCH v3 4/4] tty: serial: 8250: add DFL bus driver for Altera 16550. |
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On Wed, 5 Oct 2022, Ilpo Järvinen wrote:
> On Tue, 4 Oct 2022, matthew.gerlach@linux.intel.com wrote: > >> From: Matthew Gerlach <matthew.gerlach@linux.intel.com> >> >> Add a Device Feature List (DFL) bus driver for the Altera >> 16550 implementation of UART. >> >> Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com> >> Reported-by: kernel test robot <lkp@intel.com> >> --- >> v3: use passed in location of registers >> use cleaned up functions for parsing parameters >> >> v2: clean up error messages >> alphabetize header files >> fix 'missing prototype' error by making function static >> tried to sort Makefile and Kconfig better >> --- >> drivers/tty/serial/8250/8250_dfl.c | 177 +++++++++++++++++++++++++++++ >> drivers/tty/serial/8250/Kconfig | 9 ++ >> drivers/tty/serial/8250/Makefile | 1 + >> 3 files changed, 187 insertions(+) >> create mode 100644 drivers/tty/serial/8250/8250_dfl.c >> >> diff --git a/drivers/tty/serial/8250/8250_dfl.c b/drivers/tty/serial/8250/8250_dfl.c >> new file mode 100644 >> index 000000000000..110ad3a73459 >> --- /dev/null >> +++ b/drivers/tty/serial/8250/8250_dfl.c >> @@ -0,0 +1,177 @@ > >> +static int dfl_uart_get_params(struct device *dev, void __iomem *dfh_base, resource_size_t max, >> + struct uart_8250_port *uart) >> +{ >> + u64 v, fifo_len, reg_width; >> + int off; >> + >> + if (!dfhv1_has_params(dfh_base)) { >> + dev_err(dev, "missing required DFH parameters\n"); >> + return -EINVAL; >> + } >> + >> + off = dfhv1_find_param(dfh_base, max, DFHv1_PARAM_ID_CLK_FRQ); >> + if (off < 0) { >> + dev_err(dev, "missing CLK_FRQ param\n"); >> + return -EINVAL; >> + } >> + >> + uart->port.uartclk = readq(dfh_base + off); >> + dev_dbg(dev, "UART_CLK_ID %u Hz\n", uart->port.uartclk); >> + >> + off = dfhv1_find_param(dfh_base, max, DFHv1_PARAM_ID_FIFO_LEN); >> + if (off < 0) { >> + dev_err(dev, "missing FIFO_LEN param\n"); >> + return -EINVAL; >> + } >> + >> + fifo_len = readq(dfh_base + off); >> + dev_dbg(dev, "UART_FIFO_ID fifo_len %llu\n", fifo_len); >> + >> + switch (fifo_len) { >> + case 32: >> + uart->port.type = PORT_ALTR_16550_F32; >> + break; >> + >> + case 64: >> + uart->port.type = PORT_ALTR_16550_F64; >> + break; >> + >> + case 128: >> + uart->port.type = PORT_ALTR_16550_F128; >> + break; >> + >> + default: >> + dev_err(dev, "bad fifo_len %llu\n", fifo_len); > > I'd tell user "unsupported" rather than "bad".
The word, unsupported, sounds better. I will change it in both places you suggested.
> >> + return -EINVAL; >> + } >> + >> + off = dfhv1_find_param(dfh_base, max, DFHv1_PARAM_ID_REG_LAYOUT); >> + if (off < 0) { >> + dev_err(dev, "missing REG_LAYOUT param\n"); >> + return -EINVAL; >> + } >> + >> + v = readq(dfh_base + off); >> + uart->port.regshift = FIELD_GET(DFHv1_PARAM_ID_REG_SHIFT, v); >> + reg_width = FIELD_GET(DFHv1_PARAM_ID_REG_WIDTH, v); >> + >> + dev_dbg(dev, "UART_LAYOUT_ID width %lld shift %d\n", >> + FIELD_GET(DFHv1_PARAM_ID_REG_WIDTH, v), (int)uart->port.regshift); > > Why not use reg_width directly?
Good catch.
> >> + switch (reg_width) { >> + case 4: >> + uart->port.iotype = UPIO_MEM32; >> + break; >> + >> + case 2: >> + uart->port.iotype = UPIO_MEM16; >> + break; >> + >> + default: >> + dev_err(dev, "invalid reg_width %lld\n", reg_width); > > unsupported ? > >> + return -EINVAL; >> + } >> + >> + return 0; >> +} >> + >> +static int dfl_uart_probe(struct dfl_device *dfl_dev) >> +{ >> + struct device *dev = &dfl_dev->dev; >> + struct uart_8250_port uart; >> + struct dfl_uart *dfluart; >> + resource_size_t res_size; >> + void __iomem *dfh_base; >> + int ret; >> + >> + memset(&uart, 0, sizeof(uart)); >> + uart.port.flags = UPF_IOREMAP; >> + uart.port.mapbase = dfl_dev->csr_res.start; >> + uart.port.mapsize = resource_size(&dfl_dev->csr_res); >> + >> + dfluart = devm_kzalloc(dev, sizeof(*dfluart), GFP_KERNEL); >> + if (!dfluart) >> + return -ENOMEM; >> + >> + dfh_base = devm_ioremap_resource(dev, &dfl_dev->mmio_res); >> + if (IS_ERR(dfh_base)) >> + return PTR_ERR(dfh_base); >> + >> + res_size = resource_size(&dfl_dev->mmio_res); >> + >> + ret = dfl_uart_get_params(dev, dfh_base, res_size, &uart); >> + >> + devm_iounmap(dev, dfh_base); >> + devm_release_mem_region(dev, dfl_dev->mmio_res.start, res_size); >> + >> + if (ret < 0) >> + return dev_err_probe(dev, ret, "failed uart feature walk\n"); >> + >> + dev_dbg(dev, "nr_irqs %d %p\n", dfl_dev->num_irqs, dfl_dev->irqs); >> + >> + if (dfl_dev->num_irqs == 1) >> + uart.port.irq = dfl_dev->irqs[0]; >> + >> + /* register the port */ > > This comment is pretty useless. Just drop it.
Will drop this useless comment.
> >> + dfluart->line = serial8250_register_8250_port(&uart); >> + if (dfluart->line < 0) >> + return dev_err_probe(dev, dfluart->line, "unable to register 8250 port.\n"); >> + >> + dev_info(dev, "serial8250_register_8250_port %d\n", dfluart->line); > > This you want to drop too. It seems a debug thing rather than info level > stuff.
It is actually redundant output because serial8250_register_8250_port() produces useful output. I will drop the line.
> > > -- > i. > >
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