| Message ID | 1448372862-11912-1-git-send-email-ludovic.desroches@atmel.com |
|---|---|
| State | Changes Requested |
| Headers | show |
On Tue, Nov 24, 2015 at 02:47:40PM +0100, Ludovic Desroches wrote: > From: Wenyou Yang <wenyou.yang@atmel.com> > > Add the HOLD field management. Some i2c devices need a longer data hold > time than the one given in the i2c bus specification. Since this value > depends on the i2c device connected to the bus, add a DT property to > configure it: "atmel,twd-hold-cycles". We already have "i2c-sda-hold-time-ns". Can you use that one? Sorry that this is not obviously documented, I am working on it...
On Mon, Nov 30, 2015 at 04:13:20PM +0100, Wolfram Sang wrote: > On Tue, Nov 24, 2015 at 02:47:40PM +0100, Ludovic Desroches wrote: > > From: Wenyou Yang <wenyou.yang@atmel.com> > > > > Add the HOLD field management. Some i2c devices need a longer data hold > > time than the one given in the i2c bus specification. Since this value > > depends on the i2c device connected to the bus, add a DT property to > > configure it: "atmel,twd-hold-cycles". > > We already have "i2c-sda-hold-time-ns". Can you use that one? Sorry that > this is not obviously documented, I am working on it... > I think we can use it, I'll rework the patch to convert duration in number of cycles. -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c index 10835d1..b3595ea 100644 --- a/drivers/i2c/busses/i2c-at91.c +++ b/drivers/i2c/busses/i2c-at91.c @@ -64,6 +64,7 @@ #define AT91_TWI_IADR 0x000c /* Internal Address Register */ #define AT91_TWI_CWGR 0x0010 /* Clock Waveform Generator Reg */ +#define AT91_TWI_CWGR_HOLD(x) (((x) & 0x1f) << 24) #define AT91_TWI_SR 0x0020 /* Status Register */ #define AT91_TWI_TXCOMP BIT(0) /* Transmission Complete */ @@ -185,7 +186,8 @@ static void at91_init_twi_bus(struct at91_twi_dev *dev) * Calculate symmetric clock as stated in datasheet: * twi_clk = F_MAIN / (2 * (cdiv * (1 << ckdiv) + offset)) */ -static void at91_calc_twi_clock(struct at91_twi_dev *dev, int twi_clk) +static void at91_calc_twi_clock(struct at91_twi_dev *dev, + int twi_clk, u32 twd_hold) { int ckdiv, cdiv, div; struct at91_twi_pdata *pdata = dev->pdata; @@ -204,7 +206,9 @@ static void at91_calc_twi_clock(struct at91_twi_dev *dev, int twi_clk) cdiv = 255; } - dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv; + dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv + | AT91_TWI_CWGR_HOLD(twd_hold); + dev_dbg(dev->dev, "cdiv %d ckdiv %d\n", cdiv, ckdiv); } @@ -994,6 +998,7 @@ static int at91_twi_probe(struct platform_device *pdev) int rc; u32 phy_addr; u32 bus_clk_rate; + u32 twd_hold_cycles = 0; dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL); if (!dev) @@ -1050,7 +1055,10 @@ static int at91_twi_probe(struct platform_device *pdev) if (rc) bus_clk_rate = DEFAULT_TWI_CLK_HZ; - at91_calc_twi_clock(dev, bus_clk_rate); + of_property_read_u32(dev->dev->of_node, "atmel,twd-hold-cycles", + &twd_hold_cycles); + + at91_calc_twi_clock(dev, bus_clk_rate, twd_hold_cycles); at91_init_twi_bus(dev); snprintf(dev->adapter.name, sizeof(dev->adapter.name), "AT91");