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serial: mpc512x: cleanup clock API use 

cleanup the clock API use of the UART driver which is shared among the
MPC512x and the MPC5200 platforms
- get, prepare, and enable the MCLK during port allocation; disable,
  unprepare and put the MCLK upon port release; hold a reference to the
  clock over the period of use; check for and propagate enable errors
- fix a buffer overflow for clock names with two digit PSC index numbers
- stick with the PPC_CLOCK 'psc%d_mclk' name for clock lookup, only
  switch to a fixed string later after device tree based clock lookup
  will have become available

to achieve support for MPC512x which is neutral to MPC5200, the
modification was done as follows
- introduce "clock alloc" and "clock release" routines in addition to
  the previous "clock enable/disable" routine in the psc_ops struct
- make the clock allocation a part of the port request (resource
  allocation), and make clock release a part of the port release, such
  that essential resources get allocated early
- just enable/disable the clock from within the .clock() callback
  without any allocation or preparation as the former implementation
  did, since this routine is called from within the startup and shutdown
  callbacks
- all of the above remains a NOP for the MPC5200 platform (no callbacks
  are provided on that platform)
- implementation note: the clock gets enabled upon allocation already
  just in case the clock is not only required for bitrate generation but
  for register access as well

Signed-off-by: Gerhard Sittig <gsi@denx.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Anatolij Gustschin <agust@denx.de>
This commit is contained in:
Gerhard Sittig 2013-08-06 22:43:42 +02:00 committed by Anatolij Gustschin
parent 6391f697d4
commit 2d30ccacb1
1 changed files with 81 additions and 17 deletions
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98
drivers/tty/serial/mpc52xx_uart.c
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@ -107,6 +107,8 @@ struct psc_ops {
unsigned int (*set_baudrate)(struct uart_port *port,
struct ktermios *new,
struct ktermios *old);
int (*clock_alloc)(struct uart_port *port);
void (*clock_relse)(struct uart_port *port);
int (*clock)(struct uart_port *port, int enable);
int (*fifoc_init)(void);
void (*fifoc_uninit)(void);
@ -616,31 +618,73 @@ static irqreturn_t mpc512x_psc_handle_irq(struct uart_port *port)
return IRQ_NONE;
}
static int mpc512x_psc_clock(struct uart_port *port, int enable)
static struct clk *psc_mclk_clk[MPC52xx_PSC_MAXNUM];
/* called from within the .request_port() callback (allocation) */
static int mpc512x_psc_alloc_clock(struct uart_port *port)
{
struct clk *psc_clk;
int psc_num;
char clk_name[10];
char clk_name[16];
struct clk *clk;
int err;
psc_num = (port->mapbase & 0xf00) >> 8;
snprintf(clk_name, sizeof(clk_name), "psc%d_mclk", psc_num);
clk = devm_clk_get(port->dev, clk_name);
if (IS_ERR(clk)) {
dev_err(port->dev, "Failed to get MCLK!\n");
return PTR_ERR(clk);
}
err = clk_prepare_enable(clk);
if (err) {
dev_err(port->dev, "Failed to enable MCLK!\n");
return err;
}
psc_mclk_clk[psc_num] = clk;
return 0;
}
/* called from within the .release_port() callback (release) */
static void mpc512x_psc_relse_clock(struct uart_port *port)
{
int psc_num;
struct clk *clk;
psc_num = (port->mapbase & 0xf00) >> 8;
clk = psc_mclk_clk[psc_num];
if (clk) {
clk_disable_unprepare(clk);
psc_mclk_clk[psc_num] = NULL;
}
}
/* implementation of the .clock() callback (enable/disable) */
static int mpc512x_psc_endis_clock(struct uart_port *port, int enable)
{
int psc_num;
struct clk *psc_clk;
int ret;
if (uart_console(port))
return 0;
psc_num = (port->mapbase & 0xf00) >> 8;
snprintf(clk_name, sizeof(clk_name), "psc%d_mclk", psc_num);
psc_clk = clk_get(port->dev, clk_name);
if (IS_ERR(psc_clk)) {
psc_clk = psc_mclk_clk[psc_num];
if (!psc_clk) {
dev_err(port->dev, "Failed to get PSC clock entry!\n");
return -ENODEV;
}
dev_dbg(port->dev, "%s %sable\n", clk_name, enable ? "en" : "dis");
if (enable)
clk_enable(psc_clk);
else
dev_dbg(port->dev, "mclk %sable\n", enable ? "en" : "dis");
if (enable) {
ret = clk_enable(psc_clk);
if (ret)
dev_err(port->dev, "Failed to enable MCLK!\n");
return ret;
} else {
clk_disable(psc_clk);
return 0;
return 0;
}
}
static void mpc512x_psc_get_irq(struct uart_port *port, struct device_node *np)
@ -873,7 +917,9 @@ static struct psc_ops mpc5125_psc_ops = {
.cw_disable_ints = mpc5125_psc_cw_disable_ints,
.cw_restore_ints = mpc5125_psc_cw_restore_ints,
.set_baudrate = mpc5125_psc_set_baudrate,
.clock = mpc512x_psc_clock,
.clock_alloc = mpc512x_psc_alloc_clock,
.clock_relse = mpc512x_psc_relse_clock,
.clock = mpc512x_psc_endis_clock,
.fifoc_init = mpc512x_psc_fifoc_init,
.fifoc_uninit = mpc512x_psc_fifoc_uninit,
.get_irq = mpc512x_psc_get_irq,
@ -906,7 +952,9 @@ static struct psc_ops mpc512x_psc_ops = {
.cw_disable_ints = mpc512x_psc_cw_disable_ints,
.cw_restore_ints = mpc512x_psc_cw_restore_ints,
.set_baudrate = mpc512x_psc_set_baudrate,
.clock = mpc512x_psc_clock,
.clock_alloc = mpc512x_psc_alloc_clock,
.clock_relse = mpc512x_psc_relse_clock,
.clock = mpc512x_psc_endis_clock,
.fifoc_init = mpc512x_psc_fifoc_init,
.fifoc_uninit = mpc512x_psc_fifoc_uninit,
.get_irq = mpc512x_psc_get_irq,
@ -1166,6 +1214,9 @@ mpc52xx_uart_type(struct uart_port *port)
static void
mpc52xx_uart_release_port(struct uart_port *port)
{
if (psc_ops->clock_relse)
psc_ops->clock_relse(port);
/* remapped by us ? */
if (port->flags & UPF_IOREMAP) {
iounmap(port->membase);
@ -1190,11 +1241,24 @@ mpc52xx_uart_request_port(struct uart_port *port)
err = request_mem_region(port->mapbase, sizeof(struct mpc52xx_psc),
"mpc52xx_psc_uart") != NULL ? 0 : -EBUSY;
if (err && (port->flags & UPF_IOREMAP)) {
if (err)
goto out_membase;
if (psc_ops->clock_alloc) {
err = psc_ops->clock_alloc(port);
if (err)
goto out_mapregion;
}
return 0;
out_mapregion:
release_mem_region(port->mapbase, sizeof(struct mpc52xx_psc));
out_membase:
if (port->flags & UPF_IOREMAP) {
iounmap(port->membase);
port->membase = NULL;
}
return err;
}