diff options
Diffstat (limited to 'drivers/clocksource/sh_cmt.c')
| -rw-r--r-- | drivers/clocksource/sh_cmt.c | 88 |
1 files changed, 55 insertions, 33 deletions
diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c index 64dcb082d4cf..7b952aa52c0b 100644 --- a/drivers/clocksource/sh_cmt.c +++ b/drivers/clocksource/sh_cmt.c @@ -13,6 +13,7 @@ #include <linux/init.h> #include <linux/interrupt.h> #include <linux/io.h> +#include <linux/iopoll.h> #include <linux/ioport.h> #include <linux/irq.h> #include <linux/module.h> @@ -116,6 +117,7 @@ struct sh_cmt_device { void __iomem *mapbase; struct clk *clk; unsigned long rate; + unsigned int reg_delay; raw_spinlock_t lock; /* Protect the shared start/stop register */ @@ -247,10 +249,17 @@ static inline u32 sh_cmt_read_cmstr(struct sh_cmt_channel *ch) static inline void sh_cmt_write_cmstr(struct sh_cmt_channel *ch, u32 value) { - if (ch->iostart) - ch->cmt->info->write_control(ch->iostart, 0, value); - else - ch->cmt->info->write_control(ch->cmt->mapbase, 0, value); + u32 old_value = sh_cmt_read_cmstr(ch); + + if (value != old_value) { + if (ch->iostart) { + ch->cmt->info->write_control(ch->iostart, 0, value); + udelay(ch->cmt->reg_delay); + } else { + ch->cmt->info->write_control(ch->cmt->mapbase, 0, value); + udelay(ch->cmt->reg_delay); + } + } } static inline u32 sh_cmt_read_cmcsr(struct sh_cmt_channel *ch) @@ -260,7 +269,12 @@ static inline u32 sh_cmt_read_cmcsr(struct sh_cmt_channel *ch) static inline void sh_cmt_write_cmcsr(struct sh_cmt_channel *ch, u32 value) { - ch->cmt->info->write_control(ch->ioctrl, CMCSR, value); + u32 old_value = sh_cmt_read_cmcsr(ch); + + if (value != old_value) { + ch->cmt->info->write_control(ch->ioctrl, CMCSR, value); + udelay(ch->cmt->reg_delay); + } } static inline u32 sh_cmt_read_cmcnt(struct sh_cmt_channel *ch) @@ -268,14 +282,33 @@ static inline u32 sh_cmt_read_cmcnt(struct sh_cmt_channel *ch) return ch->cmt->info->read_count(ch->ioctrl, CMCNT); } -static inline void sh_cmt_write_cmcnt(struct sh_cmt_channel *ch, u32 value) +static inline int sh_cmt_write_cmcnt(struct sh_cmt_channel *ch, u32 value) { + /* Tests showed that we need to wait 3 clocks here */ + unsigned int cmcnt_delay = DIV_ROUND_UP(3 * ch->cmt->reg_delay, 2); + u32 reg; + + if (ch->cmt->info->model > SH_CMT_16BIT) { + int ret = read_poll_timeout_atomic(sh_cmt_read_cmcsr, reg, + !(reg & SH_CMT32_CMCSR_WRFLG), + 1, cmcnt_delay, false, ch); + if (ret < 0) + return ret; + } + ch->cmt->info->write_count(ch->ioctrl, CMCNT, value); + udelay(cmcnt_delay); + return 0; } static inline void sh_cmt_write_cmcor(struct sh_cmt_channel *ch, u32 value) { - ch->cmt->info->write_count(ch->ioctrl, CMCOR, value); + u32 old_value = ch->cmt->info->read_count(ch->ioctrl, CMCOR); + + if (value != old_value) { + ch->cmt->info->write_count(ch->ioctrl, CMCOR, value); + udelay(ch->cmt->reg_delay); + } } static u32 sh_cmt_get_counter(struct sh_cmt_channel *ch, u32 *has_wrapped) @@ -319,7 +352,7 @@ static void sh_cmt_start_stop_ch(struct sh_cmt_channel *ch, int start) static int sh_cmt_enable(struct sh_cmt_channel *ch) { - int k, ret; + int ret; dev_pm_syscore_device(&ch->cmt->pdev->dev, true); @@ -347,26 +380,9 @@ static int sh_cmt_enable(struct sh_cmt_channel *ch) } sh_cmt_write_cmcor(ch, 0xffffffff); - sh_cmt_write_cmcnt(ch, 0); - - /* - * According to the sh73a0 user's manual, as CMCNT can be operated - * only by the RCLK (Pseudo 32 kHz), there's one restriction on - * modifying CMCNT register; two RCLK cycles are necessary before - * this register is either read or any modification of the value - * it holds is reflected in the LSI's actual operation. - * - * While at it, we're supposed to clear out the CMCNT as of this - * moment, so make sure it's processed properly here. This will - * take RCLKx2 at maximum. - */ - for (k = 0; k < 100; k++) { - if (!sh_cmt_read_cmcnt(ch)) - break; - udelay(1); - } + ret = sh_cmt_write_cmcnt(ch, 0); - if (sh_cmt_read_cmcnt(ch)) { + if (ret || sh_cmt_read_cmcnt(ch)) { dev_err(&ch->cmt->pdev->dev, "ch%u: cannot clear CMCNT\n", ch->index); ret = -ETIMEDOUT; @@ -995,8 +1011,8 @@ MODULE_DEVICE_TABLE(of, sh_cmt_of_table); static int sh_cmt_setup(struct sh_cmt_device *cmt, struct platform_device *pdev) { - unsigned int mask; - unsigned int i; + unsigned int mask, i; + unsigned long rate; int ret; cmt->pdev = pdev; @@ -1032,10 +1048,16 @@ static int sh_cmt_setup(struct sh_cmt_device *cmt, struct platform_device *pdev) if (ret < 0) goto err_clk_unprepare; - if (cmt->info->width == 16) - cmt->rate = clk_get_rate(cmt->clk) / 512; - else - cmt->rate = clk_get_rate(cmt->clk) / 8; + rate = clk_get_rate(cmt->clk); + if (!rate) { + ret = -EINVAL; + goto err_clk_disable; + } + + /* We shall wait 2 input clks after register writes */ + if (cmt->info->model >= SH_CMT_48BIT) + cmt->reg_delay = DIV_ROUND_UP(2UL * USEC_PER_SEC, rate); + cmt->rate = rate / (cmt->info->width == 16 ? 512 : 8); /* Map the memory resource(s). */ ret = sh_cmt_map_memory(cmt); |