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Date: Fri, 3 Apr 2020 13:57:15 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Krzysztof Kozlowski <krzk@...nel.org>
Cc: Hyunki Koo <hyunki00.koo@...sung.com>,
Kukjin Kim <kgene@...nel.org>, Jiri Slaby <jslaby@...e.com>,
linux-arm-kernel@...ts.infradead.org,
linux-samsung-soc@...r.kernel.org, linux-serial@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] tty: samsung_tty: 32-bit access for TX/RX hold
registers
On Fri, Apr 03, 2020 at 01:53:13PM +0200, Krzysztof Kozlowski wrote:
> On Fri, Apr 03, 2020 at 01:42:37PM +0200, Greg KH wrote:
> > On Fri, Apr 03, 2020 at 08:15:10PM +0900, Hyunki Koo wrote:
> > > Support 32-bit access for the TX/RX hold registers UTXH and URXH.
> > >
> > > This is required for some newer SoCs.
> > >
> > > Signed-off-by: Hyunki Koo <hyunki00.koo@...sung.com>
> > > ---
> > > v2:
> > > line 954 : change rd_regl to rd_reg in for backward compatibility.
> > > line 2031: Add init value for ourport->port.iotype to UPIO_MEM
> > > v3:
> > > line 2031: remove redundant init value for ourport->port.iotype
> > > v4:
> > > correct variable types and change misleading function name
> > > ---
> > > drivers/tty/serial/samsung_tty.c | 76 +++++++++++++++++++++++++++++++++-------
> > > 1 file changed, 64 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
> > > index 73f951d65b93..bdf1d4d12cb1 100644
> > > --- a/drivers/tty/serial/samsung_tty.c
> > > +++ b/drivers/tty/serial/samsung_tty.c
> > > @@ -154,12 +154,47 @@ struct s3c24xx_uart_port {
> > > #define portaddrl(port, reg) \
> > > ((unsigned long *)(unsigned long)((port)->membase + (reg)))
> > >
> > > -#define rd_regb(port, reg) (readb_relaxed(portaddr(port, reg)))
> > > +static u32 rd_reg(struct uart_port *port, u32 reg)
> > > +{
> > > + switch (port->iotype) {
> > > + case UPIO_MEM:
> > > + return readb_relaxed(portaddr(port, reg));
> > > + case UPIO_MEM32:
> > > + return readl_relaxed(portaddr(port, reg));
> > > + default:
> > > + return 0;
> > > + }
> > > + return 0;
> > > +}
> > > +
> > > #define rd_regl(port, reg) (readl_relaxed(portaddr(port, reg)))
> > >
> > > -#define wr_regb(port, reg, val) writeb_relaxed(val, portaddr(port, reg))
> > > +static void wr_reg(struct uart_port *port, u32 reg, u32 val)
> > > +{
> > > + switch (port->iotype) {
> > > + case UPIO_MEM:
> > > + writeb_relaxed(val, portaddr(port, reg));
> > > + break;
> > > + case UPIO_MEM32:
> > > + writel_relaxed(val, portaddr(port, reg));
> > > + break;
> > > + }
> > > +}
> > > +
> > > #define wr_regl(port, reg, val) writel_relaxed(val, portaddr(port, reg))
> > >
> > > +static void wr_reg_barrier(struct uart_port *port, u32 reg, u32 val)
> > > +{
> > > + switch (port->iotype) {
> > > + case UPIO_MEM:
> > > + writeb(val, portaddr(port, reg));
> > > + break;
> > > + case UPIO_MEM32:
> > > + writel(val, portaddr(port, reg));
> > > + break;
> > > + }
> > > +}
> >
> > why do you have a default for the read function, but not the write
> > functions?
>
> The default for read will never happen and it returns bogus value just
> to satisfy the compiler. That's my understanding. What would you like to
> do for writes()? Print error msg? No point, it should not happen because
> of check in probe().
Consistancy please, either do it for all, or none, otherwise it makes no
sense at all.
> > > +
> > > /* Byte-order aware bit setting/clearing functions. */
> > >
> > > static inline void s3c24xx_set_bit(struct uart_port *port, int idx,
> > > @@ -714,7 +749,7 @@ static void s3c24xx_serial_rx_drain_fifo(struct s3c24xx_uart_port *ourport)
> > > fifocnt--;
> > >
> > > uerstat = rd_regl(port, S3C2410_UERSTAT);
> > > - ch = rd_regb(port, S3C2410_URXH);
> > > + ch = rd_reg(port, S3C2410_URXH);
> > >
> > > if (port->flags & UPF_CONS_FLOW) {
> > > int txe = s3c24xx_serial_txempty_nofifo(port);
> > > @@ -826,7 +861,7 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id)
> > > }
> > >
> > > if (port->x_char) {
> > > - wr_regb(port, S3C2410_UTXH, port->x_char);
> > > + wr_reg(port, S3C2410_UTXH, port->x_char);
> > > port->icount.tx++;
> > > port->x_char = 0;
> > > goto out;
> > > @@ -852,7 +887,7 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id)
> > > if (rd_regl(port, S3C2410_UFSTAT) & ourport->info->tx_fifofull)
> > > break;
> > >
> > > - wr_regb(port, S3C2410_UTXH, xmit->buf[xmit->tail]);
> > > + wr_reg(port, S3C2410_UTXH, xmit->buf[xmit->tail]);
> > > xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
> > > port->icount.tx++;
> > > count--;
> > > @@ -916,7 +951,7 @@ static unsigned int s3c24xx_serial_tx_empty(struct uart_port *port)
> > > /* no modem control lines */
> > > static unsigned int s3c24xx_serial_get_mctrl(struct uart_port *port)
> > > {
> > > - unsigned int umstat = rd_regb(port, S3C2410_UMSTAT);
> > > + unsigned int umstat = rd_reg(port, S3C2410_UMSTAT);
> > >
> > > if (umstat & S3C2410_UMSTAT_CTS)
> > > return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
> > > @@ -1974,7 +2009,7 @@ static int s3c24xx_serial_probe(struct platform_device *pdev)
> > > struct device_node *np = pdev->dev.of_node;
> > > struct s3c24xx_uart_port *ourport;
> > > int index = probe_index;
> > > - int ret;
> > > + int ret, prop = 0;
> > >
> > > if (np) {
> > > ret = of_alias_get_id(np, "serial");
> > > @@ -2000,10 +2035,27 @@ static int s3c24xx_serial_probe(struct platform_device *pdev)
> > > dev_get_platdata(&pdev->dev) :
> > > ourport->drv_data->def_cfg;
> > >
> > > - if (np)
> > > + if (np) {
> > > of_property_read_u32(np,
> > > "samsung,uart-fifosize", &ourport->port.fifosize);
> > >
> > > + if (of_property_read_u32(np, "reg-io-width", &prop) == 0) {
> > > + switch (prop) {
> > > + case 1:
> > > + ourport->port.iotype = UPIO_MEM;
> > > + break;
> > > + case 4:
> > > + ourport->port.iotype = UPIO_MEM32;
> > > + break;
> > > + default:
> > > + dev_warn(&pdev->dev, "unsupported reg-io-width (%d)\n",
> > > + prop);
> > > + ret = -EINVAL;
> > > + break;
> > > + }
> > > + }
> > > + }
> >
> > If the property is not there, the type will be uninitialized and no
> > warning will be spit out, are you sure you want to do that?
>
> The default value from initial ourport will be used, which is UPIO_MEM.
> This way it is backward compatible.
Where is iotype set to UPIO_MEM as a default?
thanks,
greg k-h
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